CIRCULAR No. 112 JANUARY 1953 PRODUCTION aj BAIT MINNOWS iot Ake SOUTHEAST A G R ICUL T U RAL E X PER I ME NT ST AT I ON a 14he ALABAMA POLYTECHNIC INSTITUTE 2. Smt V. Diect., Auburn, Alabama CONkTE NTS age HATCHERY CONSTRUCTION SELECTION. OF THE HATCHERY CONSTRUCTION OF PONDS SITE PaPG age 3 4 7 _18 Catch Basin -- - - - - - Water Supply ------ - - 13 15 Care of Brood Stock ----------- _55 .55 Stocking _55 Spawning Habits _55 Management Draining and Grading 57 Transportation PARASITES AND MINNOWS-Anchor Parasites _57 DISEASES OF BAIT Holding Facilities METHODS OF HATCHERY MANAGEMENT FOR BAIT MINNOW PRODUCTION ----------- -21 -22 Goldfish Production How to Determine the Sex of .28 Brood Fish - - - - - - 28 Goldfish Rearing Methods 59 60 Gruhs W ater M old ------------------ 60 -61 Fin Rot Fish Lice PESTS AND THEIR CONTROL --------------- 58 -58 61 GENERAL GOLDFISH HATCHERY PROCEDURES ---------------------- -37 Fertilization - ------------------ -37 Supplemental Feeding --------- _8 Draining and Grading ---------- _42 Transportation ----------------- _44 FATHEAD PRODUCTION ------------ 48 Selection of Brood Stock ------- 49 Care of Brood Stock ----------- 49 49 Stockin g --- ------------------Sex in g - - - - - - - - - - - - - - - - - - - - - - - _50 Spawning Habits -------------- _50 _51 M anagem ent -----------------Draining and Grading --------- -54 _54 Transportation ----------------GOLDEN SHINER PRODUCTION ------ -54 Selection of Brood Stock -------- -55 Insects F ro gs - C rayfish M uskrats Sn akes T u rtles - - - - - - - - - - - - - - - - - - - - - - - 61 _62 ---------------------.62 --------------------- - - - - - - - - - - - - - - - - - - - - - .62 - - - - - - - - - - - - - - - - - - - - - - _63 61 Fish-Eating Birds ------------ELIMINATION OF UNDESIRABLE FISH BY POISONING ----------------MECHANICAL FISH GRADERS ------ -64 -64 66 67 W EED CONTROL ----------------- Submerged Weeds ------------ 67 Emergent Plants and Marginal W eed s - - -- - - -- - -- -- - - - - - - -- - 68 Filamentous Algae ------------- .69 LITERATURE CITED --------------- .71 The three most important bait minnows in the South. . east: top - fathead, Pimephales promelas, Raf., also known as tuffy minnow; center - goldfish, Carassius auratus, (Lin.), also known as Indiana or Missouri minnow; bottom - golden shiner, Notemigonus crysoleucas, Raf., also known as shiner or roach. The COVER FIRST PRINTING 6M, JANUARY 1953 PRODUCTION BAIT MINNOWS i he SOUTHEAST E. E. PRATHER, 1 Associate Fish Culturist J. R. FIELDING 2 and M. C. JOHNSON, 2 Assistant Fish Culturists II. S. SWINGLE, Fish Culturist GENERATION ago minnows for use as bait were easily obtained by seining the margins of lakes, ponds, or streams. However, with the present tremendously increased number of fishermen and fishing areas, the demand for minnows not only far exceeds the supply of these natural waters, but also that of commercial minnow producers. Within the last 10 years, approximately 7,000 farm ponds have been constructed in Alabama, and new ones are now being built at the rate of about 1,000 a year. The number of ponds reported in other Southern States is even greater. In addition to these private waters, the impoundment of large areas such as those flooded by the T.V.A., Army Engineers, and other agencies has greatly increased the acreage of inland fisheries. Alabama alone has an estimated 400,000 acres of fishing waters, and currently the supply of live minnows does not meet the demand in most areas. It is conservatively estimated that fishermen would buy 20,000,000 minnows annually in Alabama, and a comparable number could be sold in each of the other Southeastern States. Obviously, efficiently operated minnow hatcheries would prove profitable to their operators. The Agricultural Experiment Station of the Alabama Polytechnic Institute has conducted experiments on production of several species of bait minnows; resulting information regarding construction and management of commercial minnow hatcheries is reported in this publication. A HATCHERY CONSTRUCTION Successful production of minnows depends to a large extent upon the physical aspects of the hatchery. Therefore, great care must be used in the selection of the hatchery site. While select2Resigned. On military leave. ing a suitable location and planning the construction of minnow ponds, considerable thought should be devoted to topography of the area, type of subsoil present, and available water supply. These are the more important features to be considered, and the area finally selected should meet certain minimum requirements regarding each. To more clearly understand the recommendations that follow concerning the construction of minnow ponds, it might be well to visualize the completed series of hatchery ponds that you intend to build. The ponds will lie in a compact unit, preferably in a row or series so that a minimum of travel will be necessary to accomplish the daily chores essential to proper management. They will be separated by well-sodded, properly constructed dams, some of which being wide enough for use as roadways. An additional road will traverse the entire series at the deep end of the ponds to facilitate removal of the minnows to trucks when harvested. Each pond will have a drain pipe for draining it independently of the others and the pond bottoms will be sloped toward the drain pipe so that all of the water and fish may be removed. The area in which the ponds are built will be lower than the source of water in order that the ponds may be filled as the water flows downhill through its conduit; each pond will have an inlet pipe and valve, which together with the drain pipe furnishes a positive and separate water control for each pond. The water supply itself will be permanent, adequate for the size hatchery involved, free of mud and all species of fish, and its chemical nature will be suitable for fish production. With this in view, the means to such a system are discussed separately, and in some detail. SELECTION ~/A HATCHERY SITE Topography. An ideal location for minnow ponds is a relatively flat, gently sloping area of bottom land (Figure 1). Areas of this type facilitate the flow of water to the ponds by gravity, allow the ponds to be readily drained, and insure good drainage of the soil surrounding the ponds. Although bottom land is desirable, boggy areas and those subject to floods during rainy periods should not be used. Unfortunately ideal hatchery sites are difficult and sometimes impossible to find in some areas, and less desirable ones may have to be used. Flat areas may be drained by the proper use [41 t<; FIGURE 1. A relatively flat, gently sloping area with a tight clay subsoil makes on ideal location for construction of a hatchery. FIGURE 2. Where the sail is sufficiently water-tight, hillsides in a terrace-like pattern. ponds can be located on of dlitches, aiid oil shairp> slojpi]Pg liiit tile poIIds n' ' he i)uilt Inl the latter ease 01n terraces arouiind tilt hillsides (Fligihre ?l b0 arried'( 1.111off water fro11 tile ponid area siol 11le locali/zed and Ct fro11 the 1111( inl ehaitels sodded to redlile erosio1. Anarea sioll) b11selectedl that is large enou)!gh to allXw for e fture expanisioni. Subsoil. An' area, 110 miatter hoXX XX ll it is adapted othcrwxise 1hatcer location, i st hlaXC a subllsoil that is elomrpact ('10!!ghi e to prex ct excessi\ e seepage, hience loss of water. Ev eii thoIgih tilt XXater sup)pl ma) beIt adel p at. to mlain0taoi thel desired wester levels ill po1)its 1)!ilt is less ilnpt'f ill!s soils, the seepage eXater w~il cIarry off mn chl of the fert ili i of tile pondits as dissolx edt salts. N ati ralk . 1 )roduletiol is Ilarked]X decreased or till as a [5] cost of fertilization becomes excessive in ponds of this type. Clay soils have a much higher water-holding capacity than other types due to the ability of the fine clay particles to fit very closely together when compacted and to swell when wet. Soils that are an admixture of sand and clay are also suitable for constructing ponds provided the clay content is sufficiently high. If a handful of moist soil squeezed into a ball and tossed lightly into the air is caught without cracking, the soil contains enough clay to make it sufficiently impervious to water. Soils that crack in such tests are unsuited for pond construction. In testing the soil in a proposed location, a soil auger or post-hole digger should be used to examine the subsoil beneath the pond area. Tests should be made at intervals throughout the entire site. At least a 3-foot layer of impervious soil of the type just described should underlay the pond bottoms. The type of top soil in an area is of less importance. Even though the bottoms of shallow ponds do not extend below a pervious topsoil, the impervious layer beneath will prevent seepage after the topsoil has become saturated. Whenever possible the clay for the dams should come from within the pond area. However, in some instances the type of soil near the surface makes this impractical. In such a case additional soil samples should be taken from near-by hillsides to determine if there is sufficient clay soil at hand from which to build the dams. Water Supply. In selecting a hatchery site, careful consideration must be given the available water supply. The source of water should remain free of mud most of the time. It should furnish sufficient water during all seasons of the year to adequately maintain a hatchery of the desired size. For the sake of economy, it should be situated so that all of the ponds may be filled by gravity flow. Possible sources of water that meet these requirements are springs, artesian wells, and streams. Springs and artesian wells are the more desirable sources of water. However, springs and streams are probably more widely used since artesian wells may be drilled in only certain areas. The quantity of water needed for any particular hatchery would necessarily depend upon the number, area, and depth of the ponds involved, and also upon the rate of seepage and the number of times the ponds are to be drained each year. It is difficult to estimate accurately the number of acres of water that can be supported by a stream of a given size. However, the [6] following estimates should be considered the minimum under average conditions: NORMAL SUMMER FLOW OF STREAM SIZE OF HATCHERY Square inches Acres 78 50 28 12 7 50-60 30-40 15-20 8-10 2-5 3 1 The normal summer flow of the stream in square inches may be estimated by multiplying the average width by the average depth in inches. CONSTRUCTION PONDS Before actual construction is begun, Designing the Hatchery. a complete survey of the hatchery site should be made and plans be drawn showing the location and size of each pond, the proposed water supply system, the position of the individual drain pipes, and the hatchery roadways. Careful planning at this stage insures the most effective utilization of the area involved, reduces costly mistakes during construction, and increases the operation efficiency of the completed hatchery. Instruments necessary to accomplish a satisfactory survey of a hatchery site include some sort of leveling device, such as a surveyor's transit and rod, and a steel tape or "chain"; in lieu of a transit, a simple farm terracing level will do very well. Care should be taken that each pond is so situated that the desired water level is lower than the water supply, thus insuring complete filling by gravity. The drain pipes should be located to discharge at a point where there is a natural grade or where a grade may be established sufficient to carry off the water when the ponds are drained. The steel tape is used in determining the total area of the hatchery site and in laying off the ponds and dams to the desired size. Sufficient space should be allocated for roadways throughout the area, and it is advisable to bring the roads as close as possible to the deep end of each pond to facilitate the removal of minnows to a truck as the ponds are drained. Clearing. All trees and brush should be removed from the areas in which the ponds are to be built. Clearing heavily wooded land is expensive at best. However, as a rule it is done more [7] cheaply by a tractor with a bulldozer attachment than by other methods. The tractor will be able to push down all brush, small trees, and stumps; larger trees should be cut and sold for lumber. If the tractor is unable to remove the larger stumps, they may be first loosened with dynamite and then pushed away. A root-rake attachment, if available, is more satisfactory than the 'dozer for piling brush and stumps to be burned. It will loosen and sift most of the soil from the roots in the process of piling. Size as Ponds. Ponds from 0.1 to 0.3 acre in size are most desirable for minnow production; however, slightly larger or smaller ones are quite satisfactory. From 100,000 to 350,000 minnows may be produced per acre under proper management. Because of the difficulty in handling large numbers of minnows while draining, ponds exceeding one acre are impracticable. Too, if all the minnows from larger ponds are not disposed of at once, considerable losses might be suffered since most mortality occurs while minnows are being held under crowded conditions. Depth of Ponds. In the Southeast, little or no oxygen is present in the water of small ponds at a depth greater than about 5 feet during summer months. This oxygenless water is uninhabitable for fish, thereby rendering the nutritive material that collects on the bottom below this depth unavailable. Therefore, the maximum depth for minnow ponds should not be greater than 5 feet, and 4 feet would be ample; in ponds of less than 4 feet maximum depth, there is some danger of losing fish during extremely cold weather. The edges of the ponds should slope rapidly to a depth of at least 18 inches to facilitate weed control along the margins. Construction o Dams. Assuming that a relatively impervious subsoil is available, seepage through dams may be kept to a minimum by proper construction procedures. The principle involved is properly joining impervious upright walls (the dams) to impervious bottoms (the subsoil), thus forming reasonably water-tight containers. The joint between the walls and bottoms of these containers is accomplished by digging a trench into the subsoil along the center lines of the dams (Figure 8), packing this trench with the best clay available and extending the core thus formed to the top of the completed dam. In effect, this is much the same as the mortise employed by a good carpenter to strengthen his work. [8] .. x .j r z, 3. side th od of as se u FGR3.Tebsfrthdasshould tec be a o clay toaor anopvioustlaye stdes oftrie pond.t usd fte damstd wattertighuea o h wa tratrwn itoe beteen he bottom andu ostuto ae.Ti he 11 iatterx stkslmiotll w oilt thee cbe toam a haX itpshe of eco ohiTIt ittl ha(It1 s V clstke. i ft ked oft stike ( off, iet \ul oere thul so fakest sewce top te widdlotth dafs houdld as biisact e used rrtoad-th Thle corhe techX ay postop itil thes seites.ii tihence tetede int tIheisubiil st of toe set-imiretakpnest Iit ous idertn theii~ dozer ae ditchlui((e i the a iticonrea ihis a iest :3i itoa the suste:r hu ofeach 11lomiXlie fee arelocatsed :3 sed beoX eo intei tieTstakes trncho the dareshould exedl If dozc isi a used) tot xat ithte tleh t i sil i becotmel tol aofT tosupport tilh tac~lto le i eht. ohal tht (ithe lcorIX tledxteoea 0.sidlit dept Intis ui )1itt th tec tile (00 least *) hut jitto tritsusi: XXt~ ilen ehameitalilierl reui e uos poif a douilr epased for blaXatetetii deite i 1)11)t sil.Thtis 19]1 material is relatively unstable and is sensitive to shock. If set in a series of holes about 12 inches apart, the series may be detonated by a single blasting cap attached to the charge in one of the holes. When the capped charge is set off, the shock is transmitted to each successive charge through the soil water. A ditch several hundred feet long may be excavated by this method (2). The depth of the holes and the amount of dynamite that should be loaded in each depends upon the desired depth of the ditch to be blown. A hole 3 feet deep loaded with two sticks of dynamite will make an excavation 4 to 6 feet deep and 6 to 10 feet wide at the top, depending upon the moisture content and type of soil. A piece of galvanized water pipe about 6 feet long, and from 1'/2 to 2 inches in diameter fitted with a steel point is a suitable tool for punching the holes to be charged. A person familiar with explosives should be consulted before attempting to excavate a core trench with ditching dynamite. County Agents and Extension Specialists are usually proficient in this field. FILLING THE CORE TRENCH. The core trench should be filled with the best clay available in the area. If the soil that was removed from the trench has a high clay content, it may be used to refill the trench: if not, better materials should be brought in from near-by hillsides. Soil may be moved from outside the pond area most economically by a tractor and pan. If necessary, the soil may be piled close to the trench by this method and then pushed into the trench with a 'dozer (back filled). While filling the trench the soil should be laid down in thin layers to insure maximum compaction. Usually a heavy tractor running back and forth while filling the trench is sufficient to pack the soil. If additional packing is necessary, a sheep's-foot or similar roller may be used to advantage. FILLING ABOVE-GROUND PORTION OF DAM. When the core trench has been filled to ground level, the bulldozer may be used to push up the above-ground portion of the dam (Figure 4). Usually one-half or more of the soil for the dams may be obtained from inside the pond area. This should be used wherever possible since this allows the pond bottom to be deepened and shaped and the dam built in the same operation. The base of the dam should be wide enough to allow the sides to taper to the desired top width of the dam at the rate of 11/2 feet in for each 1 foot in height. For example, a dam that is 4 feet high and has a top width of 6 feet should be 18 feet wide at the level of the pond bottom [10] .. , 2 2-'1 FIGURE 4. When a bulldozer is used to push up the dams, the dirt can be packed sufficiently by running the tractor up and down the sides and on top of the fill. -~2to-1, there is lFiguire 5 ). Oni dams vx'th slopes of Iress than 'heni it heconies moist. On the somne dlaiIer of the soil slipping -w e oth er hand, dam s wvith slopes of more thai II.,-to-i areni ieessam \ for) po)11(s of this t.\ p(e. and resufl'1t ini moreV shallow water where xxeedls mnay- beco me ob~jectiollable While pushing soil from wxithin the p)ond~ area, the tractor operator should use care' to lease( the p~ond bottom sloped so that all of th(e water will drain towxard tihe (Ihain pipe. If depressions are left ini the b~ottomf or it dloe's not slope sharpi\ towardl the diraini pipe. mnan mninnmows wxill remain stranded wxheii the' ponid is drained. FIGURE 5. Crass sectional diagram of a dam showing filled core trench, the drain pipe with concrete collars to prevent seepage, and a threaded standpipe far draining the pond. [ 11 ] If n eccssar\, add(ition al soil ittax be hrottght itt fromtoutside the pond1( to comtplete the duntt. The h~est elaxv shldt~ be pied along the ceonter iii e to extend1( the (ore to tbe top) of the damn. tt w ichi should b~e 12 intehes aitox c the hex el of the exater. The top of of the diat should bte plallted to centtip~ede or somte other t\ pe of ioxx growxintr grass that lormits a Ieax x sod(. Issi xi I ru\ (0 Iho xIN. Sinice moost species of ibait minlttlow\s i canniot he harx estedh ethejeontix withtout chrajilitf the pond0(1m pleteix, it is n ecessarx to hax e some tap ofC ain int each pon d. oh \'ariohts t, pes of (iraitn pipes atd v( es are osed Wxith si ccess. aIx I oxxex er, on e of the sitmplest and m1oost e cot ot ojeal t" pes fot sitmall p)ond(s contsists of a statndpi pe itnsidie tihe pon d that is attacihed 1 x ant eli to a pipe runnting heiteatht tite (lain ( Figure .5). The stand(pipe shouild be just lontg ettotgh to extend wxitiit 12 inchles of the to1) of the dalat twh iet v erticcal. Itn this p)osition it reitR) (5 tihe exeswater et tert g the pond1( and1( main tain s thte xxater lex el att the dlesire(d heighit. The pontd ittax be (Iraittd (or tie xxater iex (e] reg elatedi to at thI eigh belo th lxlni \pshing the to1) of tite stan dpipe to tite dlesiredl ptsitiot . Th readIed g.alrattze(1 ironi pipe is coitirottix utsedl for this putrpose attd has protxen satisfactory itt experimtetnttal pondt~s at A utirtn. Pipe h axrtng a diatmeter of -1 intehes is adequtate for pontd(s of 0.1 to 0.5 of atl M cre ttt si/c. ho prcet t intterfetence xxitht the b)1lildozter, the (iraini pipe cat i in i staliedh af tert h dat n i tt oll!,h twh ich it is to extettd, hIa FIGURE 6. To prevent leakage and seepage, concrete collars are poured between the clay forms and around the connecting cost iron pipe joints. 1 1-2] b~een completed: at tis time at trenc Id , bIixdug through the e (lam andl the pipe inistalledI. To prex (lit seepage along the dIraini pipe, concrete collars shoul b11 pouried at ii terx als alon g its e length ( Figure .5 ). Onhdans less than -00 feet xxide at the base txxo collars shoul b111eificien t. on e n ear each end of the pipe. so On x ider dam s thte shou ld be pot ired at 1.5-foot int erx als. Forms for the collars are easilx wade of earth ( ilgil (). The 6e collars should be at least 4 in ches thick andc shotilld extiend 65 inches on all sides of the pipe. Care shoil b11 taken to in stall e the dIraini pipe ini such a wxax that wxheel the stanidpipe is lx is( flat on the ponid bottomi, its opent ('nd lies in the dleep~est p)art of the pondi. Thiere shotl 111le at least one foiot of fall Iroi i the ('nd( of the pipe in the pond1( to its (dischuarge (1nd in order to iusire a rapid floxx of exater through the pipe wxhen the pond is being Wh'len refilli ii the dIraini pipe trench (thirou gh dan> ), the soil shotuld lie moistei ed and pi t dlowxn ini th ini, xxell-p)ac'ked lax ers to prex ('lt it froin slidlin g or xxashii i out xx heti the pond is filledl. Catch Basin A catch basinm simuilar to that shuorn Iin~ Fi gtire 7 gyreatlx facilitates the hiarx (st of minii iowxs andu recllices n iortaliht atnd( losses i' m finniowx 1)utu(ls Ti I miommiillx ' eni ii teiedl Mui id(iiii FIGURE 7. A catch basin about 12" deep and 10 -0 the harvest of minnows when the pond is drained. 'to 15-0" square facilitates [ 1:3 should be constructed around the drain pipe in the deepest part of the pond. It should be ab~out 15 feet square for ponds up to 0.3 of an acre in size. It may b~e constructed of 2 X 12-inch planks, concrete blocks, bricks, or similar material. Ilowever, it is more luralble and serv icealble if made of concrete. Both the walls and the bottom shoild be at least 4 inches thick to prev ent crackingr andl the basin should be approximately 12 inches deep. The walls of the basin shoul d niot extend above the lecel of the pond bottom so that the last of the fish and water xxill he coinpetelx wxitliin the basin xhen the pond is drained. The usual method of remoxving the minnows from the catch Iasin is by seining with an ordinary quarter-inch mesh minnow seine. 'The standipipe prexviously described makes this operation somewhat difficult. 'Where catch basins are to be uisedl, it might be expedient to replace the staldpipe wxith a gate x aix e or the less expen siv e shear-gate alxv (Figure 8). Gate xvalxes are availalle with threaded ends that fit threaded gal\anized iron pipe; hoxwever, shear-gate valves 4 r , FIGURE 8. The sheor-gote valve at left is cast iron with brass tittings for long wear. The flap may be attacked to a rod extending above water and is opened and closed by pulling or pushing the rod. The cast iron gate valve at right is brass-fitted for long service under water, and it can be operated by a rod extending above water. A revolving worm gear coens and closes the valve. The shear-gate valve (left), which is simpler in construction and cheaper, is equally as satisfactory as the cast iron gate valve (right). [14] are noi Ujil ippeci wXith th readIed (1nds an d mu st he attachedcc t the (Irain pipe b)\ concrete andc oakumi. or leaded joints. Water Supply to Springs a,#zd Streams. Since the water flowx from springs and small streams osal sspread ov er a Coilparativ ely vXide and shallowx area, it is often necessarx to imipoind the wXater at the polit from wXhiclh it is to he (diXverted in to the hatchery suoppl sX stem. This is acconplislhed easily l)\ erecting ia simall iiasom-N, or earthen clan across the stream channmel The take-off pipe for earn in g the XXater to the ponds shou ld h~e installed at foot or I more ablovec the 1ottom of the reserXvoir- to prey cot the entrance of ceessiX e sand,1 silt, and trash that normally wvill collect b~ehind( the dam. The clam should be high enough to raise the leXvel of the Xwater si ipplN an addition al 12 in ches aboXve tihe top of the take-off pipe ini order to (TMe sufficient "head," or pressure, to coiiipletelx fill the pipe. The pipe should lbe either gaX ami'ed iron, asbestos cemniit, or cast-iron soil pipe. It nieedl not be larger than the normal flo)XX of thme Xater supl)l ini (question The . pipe should he equtipped( XXitlh atXal e to regulate the floXw of Xwater inito tile ponid s\ stem.i A X alX e at this~ point is u sefoul in prey eamting I rtid(IX XXater from entering the ponids after lheaX ran us. Anm additional pipe aid X aIX c shiould1 he installed in time daui at the loXwest point ini the reser (hr ibottoml ini order to couiplctelx drain mtihe reserX oir. The sand,~l silt, and di~eb ris that iii rmialh collect bhinud damns ini flowxio .( streams Ilia\ be periodlicatllx ('lim iuted FIGURE 9. An open ditch may be used to carry water economically for considerable distance. It will be necessary, however, to keep the ditch free of wild fish and pond weeds. Hence, it should be so constructed that it can be drained completely. [ 15]1 by opening the valve on the drain pipe, which should not be less than 8 inches in diameter to facilitate the passage of these waste materials. From the point of take-off, the water may be carried directly to the ponds in pipes, or if the volume is great or the distance to be traversed is long, an open ditch, or aqueduct, may be economical (Figure 9). In either case each pond should have its own inlet pipe and valve, which may be operated independently of the other ponds. Artesian Wells. In areas where artesian wells may be drilled, the well may be capped with a pipe and valve, and the water directed to the ponds through pipes or open ditches as just described. However, in some cases dissolved iron in artesian water makes it unfit for fish production unless certain precautions are taken. The presence of this material may be detected by examining the area over which the water is discharged for a rusty brown deposit. This deposit is an insoluble form of iron that is precipitated from water of high iron content upon contact with air. If such a precipitate is present, the well water should be thoroughly aerated by running it in a shallow stream across a rocky or gravelly area at some point before it enters the pond. In most instances the dissolved iron will be removed and the water sufficiently oxygenated to render it suitable for fish production by this method. Inlet Pipe. Each pond should have an inlet pipe and valve so that it can be filled independently. This arrangement enables the operator to drain and refill any pond without affecting the others. It also prevents the movement of parasites and diseases from pond to pond, which often happens in hatcheries where the ponds drain and fill in series. Where possible the inlet should be located near the drain pipe or catch basin since large amounts of fresh water are needed when minnows are crowded in a small volume of water while being harvested. A large inlet pipe is desirable so that the ponds may be refilled quickly after they have been drained. Once the pond is filled, however, only a small stream is necessary to maintain the water level. In view of this, a 4-inch inlet pipe is recommended, but, instead of the expensive 4-inch gate valve each pipe should be equipped with a bushing that reduces the size of the pipe to 11/4 inches. The bushing is then fitted with a 1 1 nipple and a 1 /4-inch gate valve /4-inch [16] # t t FIGURE 10. A 4 inlet pipe may be used to till the pond, and a bushing equipped with a 1 4 nipple and gate valve then screwed in. The gate valve may be regulated to maintain the water level. F~iure 1(0 \\ 1cnii\ cr i 4-inceh striami is nleedled, the lbusliinw }. is reiiiox Cd, whejn the pond has filled, the lnishilig is replaed't and the vviater lex ti is InanI taiI Ied 1bx reuiatimIw the i1!l-iic aix e. elv Water Filter. O )le o1 the prime re(1 luisitt's for produc tioni of 001io\X s is that tie ponds be kept free of other p(eies of 1 fish. \Vherex er the souirce of xxater is artesian wx or smuall tlls springs ini wxhich no0 fish arc present, no fuirthier precauitionis are' liecessarx . H oxwexer. most larger springs and streams are poputlatedi bx xxild fish amid sonic method must b~e usetd to prex t'it these fish frotm t'lIt(riligf the nioiioxx ponds. Tihe uistual tet llex iii 1011 ha~tchery operators is to tic a piece tof sereeniwxire around the inlet( pipe to ('ach p)ond to prex emt eontamination bx uindesiraii ti species. Th is mnetihodtl thoiuigh b ette'r tiani none, has not b~eenI found1 to he ('fietix e in exeluidinig the iiexx ]"-liatehed fry of moit species of fish. Gray el filters ( Figurre st 11) hox\ excr. hax e prox ed x( er> satisf actorx for this pi irpose if ipiop'd 'on~strutied. Thex shld~lt he inicluided as an imipor'tant teatuire ini all minimnow pond~s. lT'e filter slhown ini Figurme 11 is mereix a chiiitlex of 1bricks em iclosiug the inlet pipe and (Ixaixe. The echimnimex should be blliilt on1 at coierete footingr. It shouiltd be about ~4 inic'hts sqfuare amnd shouild h(' high c'mioimgi to ex\te'td 24 inches ahoxc w xatt'r lex el wxheni the pon d is full. () thei sicie of the filter axxax fron the pond edg('. tiit bric'ks ini the b~ottom txwo b ait [1 1 a..- FIGURE 11. A grove titer similar to the Gne above should be used to prevent the entry of wild fish into minnow ponds. The filter must be periodically cleaned to maintain its effectiveness. lax ers should1( he set appro~ im atelx 2 iniceles apart to al1 lxm the \x ater to flow from the filter inlto thle pond1 after passimi thirol ogl tilt g~rax el. T1e elliiiex should be filled to tihe pond~ wxater lex el xwithi gra\ dl I inceh, 01 less, iln diamieter. Grax el less thall 1 ineh ini diameter tei (s to lbeeome (jlliekbl\iogged wxithl silt and deb(i'ris, whieh iiiax eause some dlaiger of tihe wxater flowxing ox ei tile top of the filter and~ eonltamlinating the pond x t x l fish. [or thlis reasonl . it sailh .ecsr rod,. pipe, or shovxel should be kept onl hanld for this plurpose. Tihe effort (eleudd ill 1llailtaillill the filter p~roperly xxiii pay big (lixidlend(s ill inlereasedl mlaintai tice irPon n1lloxx produlcltionl. proper floaxv of xxater. .fin opridcaksi tihe grax el ini filters toi Holding Facilities Faili ties to xxhIich tihe fish luaut be1 reililx ed xxheni the pond(s arie chinled muidst bie axvailale at all llililox hlatcheries. These faeilities must not oly b~e adeojiiate to hold all oft tile illiilloxxs froml tihe largest pondc onl tile Iatellerxr 1but at tile samle time Ibe comfpact enoul~ghl to alloxx easx reiiox ai o)1 minnfoxxs ini relatix elysmlall nu~mbfiers for coun~tintg, sor tinlg iinto size groullps, and sale. L1tS Prohably the cheapest t, pe of holding facility and one that is especially su ited to hatcheries with small wxater' su pplies is a pool ,v ith ('arthien sides and~ bottom and~ similar to the rearing ponds(1. lIn this pool the iinoxxs are held ill xxire cages ( l'igiure 12 ). The size of pool reqi redl of course. (lepend on5 the IInmber 1 of, mnnowxs that would1( be oIL hand at ainx one time. I Ioxxex er, regrardless of the surface area, the depth should be at least 4 feet to p~rox ide a \ 01110 of wlxxater large enou1gh that wxill b~enot come easilx fou led by the feces and respil atorx wxastes of tlhe muii iowxs. Thme cages should be made of light weight material, suich as 2 2-inch lumb ier or small nmetal rods coveored wxith I,. inch hardwxare cloth . Thex xxill last much .ilo nge~r if treated wxith tar. LLoldli1Lg cag~es a1)lro~imatelx 2 feet wxide, 3 feet (deel). and~ 6 feet long Lre of a desir able size. TIhey are large enoulgh to hold sexveral hundred to sex ('Ial thuolsaInd minnLIowxs and xet small enough to 1be easilx lifted inl (LIut of the pool. The cages shld~~ or 1 e suspended at least a foot ab ox e the ponI d b ottom) to allow thme feces to fall thriouighL. Th~ey sholLd be1 inI(asx reach so) that the hatchmery IoanI Ila Ld\(ip mmii noxxs froml thmL xxithout xxad(ly inl the pool amnd causing the xxater to b~ecome nuddx. Ill addition to hmax mg iaroxw of cages aloIe, the margxn wakaxs or ocr L r 0 -Ii aF Yfs A - / 4.y' FIGURE 12. Holding cages for minnows ore mode approximately 3'-0" wide, 6'-0" long and 2'-0" deep. They should be covered with smooth, quarter-mesh hardware cloth. These cages should be suspended 1V-0" Cr more above pond bottom. [t ] FIGURE 13. Ar remnt that is used at the G~ish Minnow Haltchery, Athens, Ala., for holding minnows in an earthen pond. The screened arco tends to prevent theft and the spray falling in and around the holding cages aerates and circulates the water. 3 y FIGURE 14. Concrete holding pond, holding cages, and overhead sprinkler sysMoa. tern that are used at Clark's Minnow Hatchery, Decatur, This pond can be drained and cleaned when necessary. additina] holding space is i ceded. A siiuple sprinlerh~ systeim 11( c in stall'd sex eral o)1perforate'd ga]\tli tie i ron pi pes shoul [201 feet above the cages; water from the pool is sprayed onto the water's surface in and around the cages (Figure 13). A small electric centrifugal pump may be used to circulate the water through the system. The number of minnows that may be held in cages of the size just described and the number of cages per unit area will vary from hatchery to hatchery. However, a little experience will enable the hatcheryman to determine the number that may be held in his particular pool. A more expensive but perhaps a better holding facility is a concrete pool large enough to hold the desired number of cages (Figure 14). The pool need only be deep enough to fill the cages to within about 6 inches of the top when they are suspended 2 to 3 inches above the pool bottom. Fresh water is allowed to enter continuously in pools of this type, the foul water being carried off by a discharge pipe set even with the bottom of the pool. The desired water level is maintained by a standpipe installed outside of the pool. The fresh water entering the pool should be sprayed in and around the cages by an overhead sprinkler system. This type of pool is suited only to hatcheries having a large, permanent water supply. Holding pools should be located as close to the counting and sorting sheds as possible. They should be protected from fish-eating birds and other animals by fences or other devices. Minnows in the quantity desired may be removed from the cages with long-handled dip nets. The dip nets should be square or rectangular to permit dipping in the corners and along the sides of the cages. Fine netting is available from most of the large net and twine companies. It should be used on the dip nets because coarse material will scale the fish, causing them to be more susceptible to disease. METHODS j HATCHERY MANAGEMENT BAIT MINNOW PRODUCTION a04 Good minnow pond management is impossible, or extremely difficult, with poorly constructed ponds or inadequate facilities. On the other hand, the best minnow plant that could be built would be an unproductive aquatic farm without the application of the proper techniques of stocking, rearing, handling, and disposing of minnows. It is not the purpose of this circular to emphasize either hatchery construction or pond management, but to treat them as an integrated system of minnow production. Propagation and rearing of minnows is not an exceptionally [211 complex procedure. By using proper techniques, however, production per unit area may be markedly increased over haphazard methods. Detailed methods of hatchery operations for the production of goldfish, fathead, and golden shiner minnows have been developed at this Experiment Station. These methods as well as information on parasites, pests, and their control and related subjects are presented in the sections that follow. Goldfish Production The goldfish is perhaps the best species of minnow to raise commercially for bait in the Southeastern States. It lives well in crowded containers even during hot weather, reproduces in large numbers in small ponds, and attains a desirable size within a few months. Depending upon the size of the minnow, it can be used as bait for crappie, catfish, jackfish, and bass. Since goldfish and carp belong to the same family (Cyprinidae), many people have the mistaken idea that the two fish have similar habits and that the goldfish will, therefore, root around on the pond bottom and cause the pond to be muddy. Even in very crowded rearing ponds, however, goldfish do not roil the water. Although there are numerous published statements to the contrary, experiments at Auburn, Alabama, over a period of 12 years have shown that goldfish are not harmful to ponds and lakes stocked with largemouth bass and bluegills. Observations on several hundred ponds and lakes in the Southeast in which goldfish have been used for bait by fishermen have shown that this species was not detrimental since the numerous bluegills prevented the goldfish from reproducing successfully by eating their eggs (5). The few goldfish that evaded the largemouth bass often grew to a size of 3 to 5 pounds each, but in no pond had the goldfish become numerous or harmful. Florida prohibits the use of goldfish and some other states may also limit their sale. Therefore, local regulations should be checked before a goldfish hatchery is contemplated. Such information may be obtained by writing the state game and fish commission or from the local county judge or game warden. In the production of goldfish for bait, there are several methods that can be used to rear the young. These methods may vary with the individual operator, but regardless of the method used there are certain features that are common to all methods. These features will be discussed under the following headings: spawn[22] iiig habts, selection of brood stock, raising lbrood stock, wintering brool stock, and sexing. Spawning Habits. Goldfish normally begin laxying eggs when the xw ater temnperature approaches 60 -". in the spring. Thex' will cointiinuei to spawin throughout the suinmer x'hile the xater teimiperatuire is aboxve 6(J F. if well fed and not crowdned by either other adults or yolntg goldfish. At Ahurn, Ala., the first FIG. 15. Spawning mats are constructed by making a rectangular wooden frame approximately 18" x 36" of 1" x 2' stock. A strip of 1" mesh chicken wire 6" x 3'-0" covered with Spanish moss, wood excelsior, or similar material is stapled to this frame. FIG. 16. The spawning mat is staked along the edge of the pond within easy reach. Goldfish are shown below swimming across the pad of Spanish moss in the act of spawning. ;I / I 23] goldfish eggs are usually found in late February. However, each year most of these early eggs are killed by subsequent cold weather, leaving only a small number of young goldfish from these early eggs. The peak of egg laying occurs on sunny days in the early morning just after sunrise, although eggs also may be deposited in the late afternoon or at any time on cloudy days. As the laying period approaches, the males may be observed "driving" or chasing the females around the pond. In early spring, when the water reaches about 60 ° F., the female begins laying eggs on grass, roots, leaves, or similar material. The eggs are fertilized almost immediately by the males. The eggs are adhesive and stick to any object they touch. In the absence of grass, leaves, or roots, the eggs are laid along the edge of the pond just under the water surface and adhere to rocks, sand, or clay on the pond bottom. Consequently, it is essential that the water be maintained at a constant level during the spawning period in ponds where floating or submerged mats are not used to collect spawn. Spawning mats are light-weight wooden frames, rectangular or square in shape with a narrow band of chicken wire or some similar material across the middle of one side (Figure 15). Spanish moss, excelsior, or grass is attached to the chicken wire with twine. These mats should float with the padded side up and about 2 inches beneath the surface of the water (Figure 16). They should be staked around the edges of the pond (Figure 17) at the rate of four to eight per 0.1-acre pond. The number of spawning mats in a pond should be sufficient to prevent the eggs from overlapping as this reduces the hatch. Since the eggs are adhesive, they adhere to one another quite readily and where they are touching the percentage of hatch is lowered. At water temperatures of about 60 ° F., eggs usually hatch in 6 to 7 days. Only 3 days are required for hatching when the water temperature increases to about 80 ° F. The eggs are clear when laid. As they develop a brown spot forms in them but the margins remain clear. When the egg is not fertilized or the embryo dies, the egg turns cloudy and opaque. The dead eggs become covered with mold if allowed to remain in the pond for several days (Figure 18). Each female may deposit 2,000 to 4,000 or more eggs at a single laying and may spawn several times in the spring. The parent goldfish give no protection to the eggs or young fish. If [24] ~" c. 4, .. 'N FIGURE 17. Where goldfish eggs are to be transferred (Methods II and III), the sides of the pond are boarded up so that the goldfish cannot lay on grass or roots along pond edge. Spawning mats are staked inside the board-enclosed area at the rate of 4 to 8 per each tenth-acre pond. 1 ,l , zi~-- ~I ,Tb~;~t bgR ": kb 'z i . i,:,, ia--~" caa.r L~ ~; FIGURE 18. At left ore good, live goldtish eggs as they appear on Spanish moss. Right: Dead goldfish eggs turn white and become covered with mold. CMT.(S tit to otlher pondls, spawiiig istiall\ (.1)1era]l weeks or tintil the frx are al)Oit I lciih loiig. WVhen that size is rcaebed, the frx hegiil to eat the eggs. ainl the 1roo(1 fish cilit la ig. uThe fact that goldflsh (1 Iqit spaxxill wheigw n ari not trl~lslerf('( u's for sex [ 25 1 crowded is a unique method of birth control not too well understood. When eggs are laid on mats and are transferred from brood ponds, egg laying continues over a much longer period, but usually it decreases after about 1 or 2 months. This is apparently caused by hatches of young in the brood ponds or the accumulation of chemical agents preventing reproduction. Spawning can be started again by flushing out the pond with fresh water, by partially draining and refilling with fresh water, or, where small fish are present, by transfer of the brood stock to freshly filled new ponds. Hatches have been produced by this method as late as October 15 at Auburn. However, the later in the year the brood stock were transferred, the smaller was the number of eggs laid. Selection aj Brood Stock. Goldfish approximately 8 to 12 inches long, weighing 1/4 to 3/4 of a pound, are the most desirable as brood fish, although smaller ones about 4 inches long can be used. Initially, these brood goldfish can be purchased from some hatchery as adults or raised from fingerlings. They should be examined with care because they should be free of external parasites (see page 58) and be in good condition. In many cases the selection of parasitized brood stock has resulted in the loss of the entire crop. Once these parasites are introduced, it is necessary to destroy the brood stock and poison the pond to eradicate them (see page 64). The importance of obtaining brood fish free of parasites cannot be overemphasized. Fishermen seem to prefer the common dusky brown- or strawcolored goldfish for bait rather than the highly colored red ones, although fish apparently are not as particular. Fortunately for the bait raiser, only small percentages of the young minnows are so highly colored as to be objectionable to the average fisherman. However, in stocking ponds, brown-colored brood fish should be used. Raising Brood Goldfish. To raise brood stock, large selected brown goldfish fingerlings should be stocked in ponds chosen for this purpose. These ponds should be stocked in the summer at a low rate and be fertilized and fed. This is necessary so that the fish will grow rapidly and will be suitable for use as brood stock during the second year of growth. New brood fish for replacement will have to be raised annually since there is a loss of about one-third of the brood stock each year. [26] The procedure for raising brood goldfish is as follows: (1) Stock selected brown goldfish minnows at the rate of 5,000 per acre. (2) In Alabama, stock the ponds approximately August 1; for areas farther north, stock up to one month earlier. (3) Fertilize with the equivalent of an 8-8-2 fertilizer (see page 38) at the rate of 200 pounds per acre per application. The first application should be applied when the pond is filled. The second and third applications should follow at 2-week intervals; subsequent applications should follow at 3-week intervals until the water temperature drops below 500 F. (4) Feed soybean meal or hog supplement-poultry laying mash mixture (see page 89) at the following rates for Alabama and neighboring states: Rate per acre per day Month 10 lb. First (August) -......... 20 lb . Second (September) 30 lb. Third (October) 40 lb. Fourth (November) 30 lb. Fifth (December) (Check ponds and reduce feeding when food is not being utilized because of low water temperature.) (5) Drain pond in December, or January, and concentrate fish in a wintering pond. Wintering iMe Brood Stock. The brood fish for the current year's production should be concentrated in small wintering ponds and kept in a crowded condition during the period of January to March. Thiis necessary to prevent, or at least reduce, egg laying until the danger of cold weather is passed. Where this is not done, goldfish may lay heavily during the first warm days in February or March and subsequent cold weathey will kill most of the eggs. As a result only small numbers of goldfish hatch. After the young fish are a few days old they will eat practically all eggs subsequently laid or stocked in the pond. While the fish should be kept crowded, they must also be kept in good condition if heavy egg production is to be expected. This makes feeding necessary while the fish are in the wintering ponds. [ 27 ] The procedure for wintering brood fish in the Southeast where ice and snow are not problems is as follows: 1. Select for wintering ponds 0.1-acre ponds with steep sides, free of trash and grass and with depths not over 5 feet. Fill with water. 2. Stock each 0.1-acre wintering pond with 3,000 to 5,000 brood fish in late December or January. 3. Feed the brood stock in these ponds each day with 6 pounds of soybean cake or meal, or with a mixture of 3 pounds of hog supplement and 3 pounds of poultry laying mash. If the fish are not utilizing the food, the rate should be reduced. 4. Subsequently, regulate the water intake so that the water level is maintained but do not allow a heavy stream of water to flow through the pond as this will stimulate spawning. 5. Drain the wintering ponds when severe cold spells appear to be over (the last of March at Auburn, Ala.). 6. Transfer the brood fish immediately to the brood ponds (see page 30) or the combination brood and rearing ponds. How to Determine the Sex ol Brood Fish During the spawning season, males may be easily distinguished from females by the presence of tiny tubercles, commonly called whiskers, on the sides of the head and on the front edges of the pectoral fins. These tubercles are quite small and both look and feel like tiny grains of sand or a stubble beard. They are present only during the spawning season. Goldfish Rearing Methods Three methods of rearing goldfish are explained. differences among the three methods are as follows: The basic METHOD I, (Simple Combination Method). Egg laying, hatching, and growing of young to bait size all occur in the same pond. METHOD II, (Egg Transfer Method). A brood pond is provided for egg laying and the eggs are then transferred to separate ponds for rearing the young to bait size. METHOD III, (Fry Transfer Method). A brood pond is provided for egg laying, the eggs are transferred to hatching ponds [ 28] and troughs, and the newly-hatched fry are subsequently moved to rearing ponds. Factors influencing the selection of the method used are the amount of pond space available, the know-how of the producer, and the demand for bait. Probably Method I is in widest use because it is adapted to the needs of a small inexperienced producer. Large producers may use either Methods II or III since they allow better utilization of pond space. The new producer must consider his own situation and select the method or combination of methods best suited to him. METHOD I, (Simple Combination Method). In this method the pond is stocked with brood goldfish at the rate of 200 to 300 per acre after danger of frost has passed. Sexes should be approximately equal in number. Spawning mats should be placed in the ponds to supplement the grass and trash already present. The young fish are allowed to hatch out and remain in the same pond with the adults. This method is quite simple, takes very little experience or supervision, and may be used in both single ponds or in a series of ponds. The disadvantages of this method are that there is less control of the number of young produced and more of a possibility of parasites being transferred from adults to young. Parasites may become a serious problem in hatcheries where adequate measures are not taken against introduction and for control. From this method production of 80,000 to 350,000 with an average of 120,000 bait minnows per acre may be expected from one crop. The poundage and resulting size of the minnows depend on the rate of feeding and fertilization, and whether one or two crops are raised each year. Just as many pounds per acre can be raised by this method as by any other under normal conditions; but due to variable hatches there is danger of raising oversized fish unless the ponds are examined monthly and rates of feeding adjusted. When ponds are managed by this method, regular fertilization (page 38) and supplemental feeding rate No. I (Table 5) should be followed. Periodic checks on the size of the minnows with a seine will assist in proper management. From the average size of goldfish found in the seine, the feeding can be increased or decreased to obtain the size minnow desired. If only one crop per year is to be raised, the goldfish should reach a desirable size by December so that they have 2 months in which to "harden" before harvest. "Hardening" is a process whereby [ 29] goldfish that are grown rapidly are carried on a reduced feeding program for from 2 to 4 weeks. This causes a small loss in weight but produces a hardier minnow. In any event, fertilization should not be stopped until cold weather as this represents the cheapest form of production. The procedure for rearing goldfish by Method I is as follows: 1. Fill the pond about March 1, or 1 to 2 weeks before stocking and begin fertilization immediately at the rate of 200 pounds of 8-8-2 per acre or its equivalent. Second and third applications should follow at 2-week intervals and subsequent applications at 3-week intervals until the pond is drained or until the water temperature drops below 50 ° F. in the fall. 2. Stock the brood goldfish at the rate of 200 to 300 per acre (1/ males and 1/ females) after the danger of frost is passed. (The last of March at Auburn, Alabama.) 3. Immediately after stocking start supplemental feeding at the rate of 10 pounds per acre per day (see feeds, page 39) and subsequently adjust to obtain the size of minnow desired. 4. If the minnows are of usable size and the demand warrants, the minnow ponds can be drained 2 to 4 months after stocking (about July 1-15 at Auburn, Alabama) or they can be carried over to the fall, winter or spring. 5. Ifthe crop is harvested in the summer, the pond should be refilled and restocked as is shown in steps 1 and 2 above. 6. The second crop will be ready for harvest the following January to March. METHOD II (Egg Transfer Method). This method requires a series of at least 8 to 10 ponds and considerable experience in hatchery operations; also daily supervision is a necessity during the spawning season. Its advantages are that some control over the number of goldfish in a pond may be exercised by regulation of the number of eggs stocked, and the transmission of parasites from brood fish to the young is reduced. The brood goldfish are stocked after the danger of frost is over unless heating facilities are available to hatch eggs in the event of sudden cold. Depending on their size, they are stocked at the rate of 300 to 2,000 for each 0.1-acre - that is a 0.3-acre pond would be stocked with 900 to 6,000 brood goldfish. The brood ponds should be boarded up around the sides from 2 feet below to 1 foot above the water level and'the grass and trash in the wa- [ 30] ter removed to discourage spawning other than on the spawning mats. Spawning mats to collect the eggs are staked around the pond at the approximate rate of 4 to 8 for each 0.1-acre (Figure 17). The mats are transferred to rearing ponds twice daily and the young minnows hatch and are reared in these ponds. Since the goldfish may start eating eggs soon after the absorption of the yolk sac, additional mats should not be transferred to a rearing pond for more than 7 days after the initial ones. The rearing ponds should be filled just prior to the transfer of the spawning mats. This prevents an accumulation of aquatic insects that destroy the eggs and young goldfish. As the mats are transferred, the total number of eggs should be estimated. Normally, only half of the eggs transferred from brood to rearing ponds can be expected to survive; thus a production of not more than 200,000 to 300,000 goldfish per acre can be expected from a transfer of from 400,000 to 600,000 eggs. Before the pond is stocked, the size goldfish that will be most readily salable should be known. Then with one of the regular fertilization and feeding programs the pond can be stocked to obtain the maximum number of minnows of the desired size. Suppose, for example, it is desired to produce goldfish 2.1 to 2.4 inches long, using fertilization plus a heavy rate of feeding (Rate III, Table 5). In Table 1, the number of eggs that must be stocked to raise approximately this size minnow is given as 675,000 per acre. If the pond is 0.2 acre, then the number to be stocked will be: 675,000 X 0.2 = 135,000 eggs On the average, half the above eggs or newly hatched fish will die, resulting in approximately 67,500 minnows of the desired size TABLE 1. THE ESTIMATED NUMBER OF EGGS THAT SHOULD BE STOCKED IN REARING PONDS TO PRODUCE MINNOWS OF VARIOUS SIZES FOR GIVEN POND TREATMENTS Pondtreatment Pond Soybean meal Rate I (2,580 lbs.) Rate II (4,470 lbs.) Rate III (6,410 1bs.) - Production per acre Eggs to stock per acre to obtain bait minnows of the following average total length in inches 1.6-2.0 2.1-2.4 Number 550,000 650,000 675,000 2.5-2.8 Number 800,000 340,000 350,000 2.9-3.2 Number 200,000 250,000 260,000 3.3-3.6 Number 150,000 175,000 190,000 Pounds Number 1,800 850,000 975,000 2,100 1,000,000 2,250 1 All treatments received fertilizer at the rate of 2,600 pounds of 6-8-4 and 130 pounds ammonium nitrate per acre. (See page 38.) 2Feeding schedules for the rates are given on page 41. E31 ] in the 0.2-acre pond at harvest. It must be kept in mind that the presence of large number of predaceous water bugs or of wild fish will greatly reduce the survival of goldfish. Where this occurs, a smaller number of goldfish of larger size will result. The procedure for rearing goldfish by Method II is as follows: 1. Select as brood ponds 0.2- to 0.4-acre ponds with steep sides, free of trash and grass and with depths not over 5 feet. Board up the side of the ponds from 2 feet below to 1 foot above water level. 2. After the danger of frost is passed, stock prepared brood ponds with brood goldfish (equal numbers of male and female goldfish) at the rate of 300 to 2,000 per 0.1-acre. With the heavier rates of stocking, a constant stream of fresh water must be run continuously through the brood ponds during the egg-laying period to stimulate heavy spawning. 3. Fertilization should be started in the brood ponds at the time of stocking and continued until frost in the fall (See Fertilization, page 37). 4. Feeding should be started in the brood ponds at the time of stocking and continued throughout the summer at the rate of 6 pounds of soybean cake per 0.1-acre per day. 5. As soon as the brood fish are stocked, spawning mats should be added to the brood pond at the rate of 4 to 8 per 0.1-acre. 6. Examine the mats at least once and preferably twice each day. When eggs are found (see Figure 18), the number on each mat should be estimated, and the mat should be removed and replaced with a new mat. 7. The mats bearing eggs should be moved to the freshly filled rearing pond. Exposure of the eggs to air for periods not in excess of 30 minutes is not harmful to the eggs, if they are shaded from strong sunlight and protected from drying winds. 8. Mats should be staked in rearing ponds, as illustrated in Figure 19, so that they will float up or down with changes in water level, yet may be easily reached from the bank for removal after the eggs hatch. 9. After the eggs have hatched the mats may be removed from the rearing pond. 10. All eggs should be placed in a given rearing pond within a 7-day period. 11. Spawning mats can be transferred to new rearing ponds throughout the summer as long as spawning continues. When C32] c j Iwo - «. Ark ,.-. , FIGURE 19. Mats containing eggs are removed from the brood ponds daily and are staked out in a rearing pond, as shown here. After the eggs hatch, the mats are removed, dried in the sun, and are then again ready for use. (lecea(ses or steps ill Jtilx or Xtugutst and~ tile lrood fish ar(' inl good condition, tile b)1oo( 1)ond should lbe e~amliuted for tile preslilee of smiall fish. Ifs smlil fish are presen t spawilon g call uisually be startedl a(4aill b lIN IFitii thecbrood pondi, relilm\ill" all fish at d tilet rcfillil " anid rehurnit 2 thle brood( stoek to the pondi. If no smiall fish are presetit, spaxxnilig ean lbe illdutIed b\ partialN drainii i and( refilinl£ the plonid wxith fresh xs ater. spaw tnilt 12. Fertiization of the rcainlw2 pond should be bcpm ime dliately aftei it is filled should be cot iited unitil thle pondI~ is dtained orunitil the first frost (see 1ertili,atiou, 3i for antd palxe rates and1(freuquute\ 1 1b. 1eedio1(2, aeeordlil 0 to the selected pro ramn (either rate I, II, or Ill.I lahble .5 ) should begin imtnediatelx after the( Iearitlnr pondsl are stocked tuid eoittinu unIltil tihe pondI is drainedc. Sam\v-itli a seine to dletermlinle the size of tie niitiow s k\ill iticaeite wh Iethler the( feediiig iate nleeds to be rcugiulated. If foodl is nlot 11(11 (uI tilized, thle feedilwe rate shotuld1 be redu edl if tile mnnlows ate n ot 2Fow in£2 at a satisfactory rat( it shol b01( e pliIs2 increased. 14. The crop) of fishl can 1be partially lhar\ ested b)\ seinil (fafter somle of tile mlinntows are of salable size. Thle lark mhinntowxs to be reio ed ean be separ atedi Im tile use of fish g~raders ( pa~rc 66). ~ [5. Whleii a pond~ is drained it should 1)e allowedl to renainl (lry or should he partialix refilled and poisoned ( page 64 ) to kill the relmainingl( fish. 16. Whlein a rearing pond is dIrained ini the slimmer ( JuneSeptember 15), it can lbe restocked using the samve procedures followxed in the spring if eggs are ax ailalhle. \Iii iin 111. ( Fri Tranisfer Mtethod) In Mlethod III as in MIethod If the brood fish are conicelttratedl in b~roodl ponds (luring the egg-la. ing period. I loxx exer, in this method, wh1en the nmats ioy ('redl wxitht eggs are transferred theN are placedl in tanks or troughs xx here the egg hatch. IThese tanks mlax be cox erel or the wxater s d e tool prex o t theT(death of eggs ry h t heated . ixsr s e and niewix ,b t dl frfo tc e hatche h iae r there is nio attempt to raise tiiimoxx s for market ini 3 or 4t oths. (arlx1 hatches are n ot i ecessarx. After the frx are 3 to 3 (laxs old the iiiihers are carefilix estiuiatedl and thcv are trantsferred to rearin g potnds. The nitml )&r of goldfish catl 1e estim ated with sufficient accuiracv bx counttitng a gix ecn n1t tiiler itnto a whitebottom pan conttaiing 1 to 2 inchtes of xx ater anid theni adding fish to similar panls until thex appear to contain ((qual nlitithers (Figure 20). While mnatching the ttlimblers, the pans should be rotatedl sli ghly to catuse th e fish to arratnge then seix es itnore or less t itifortnlx throuighiout the xx ater. With a little practice the itnt1 )ers canl 1 e estimated wxithi less that i a 10 per ccitt error. Fri shuuld hec hand~led1 carefIllx xxith fine uli on tettinig or bx ~-7 A6A FIGURE 20. In transferring goldfish fry to rearing ponds, the numbers are estimated by comparison, as shown here. Into the pan at left, 500 minnows were carefully counted. Without counting, minnows were then added to the pan at right until their density appeared equal to that on left. The actual number in the pan at right was 489. [34]1 use of a dipper to prevent heavy loss. In handling fry an average mortality of 25 per cent should be expected and allowed for. This method requires more labor than either I or II because of the extra step. The advantages are that early hatches are possible where heat or protection from cold is available, the numbers stocked may be controlled and the transmission of parasites to the young from the brood fish is greatly reduced or eliminated. If the desired length of salable minnows is known, refer to Table 2 for pond treatment and numbers of fry to be stocked to produce this length minnow. For example, if fertilization plus soybean meal, Rate III, is the treatment to be used, approximately 700,000 fry will have to be stocked per acre to obtain a production of 2,250 pounds of minnows averaging 1.6 to 2.0 inches in length. TABLE 2. ESTIMATED NUMBER OF FRY THAT SHOULD BE STOCKED TO PRODUCE MINNOWS OF VARIOUS SIZES FOR GIVEN POND TREATMENTS Pond treatment' Production per acre Number of fry to stock per acre to obtain bait minnows of following sizes. Total length in inches 1.6-2.0 2.1-2.4 2.5-2.8 2.9-3.2 3.3.-3.6 Soybean Meal Pounds Number Number Number Number Number Rate I (2,5301lbs.) 1,800 550,000 350,000 200,000 140,000 100,000 Rate II (4,4701lbs.) 2,100 650,000 425,000 225,000 160,000 110,000 Rate III (6,4101lbs.) 2,250 700,000 450,000 250,000 170,000 125,100 1 All treatments received fertilizer at the rate of 2,600 pounds of 6-8-4 and 130 pounds ammonium nitrate per acre (see page 38). 2 Schedules for the feeding rates are given on page 41. The procedure for raising goldfish by Method III is as follows: 1. For brood ponds select 0.2- to 0.4-acre ponds with steep sides, free of trash and grass and with depths not over 5 feet. Prepare the ponds by boarding up the sides from 2 feet below to 1 foot above water level. 2. After the danger of frost, stock prepared brood ponds with brood goldfish (approximately equal in sexes) at the rate of 300 to 2,000 per 0.1 acre. With the heavier rates of stocking, a constant stream of fresh water must be run continuously through the brood pond during the egg-laying period to stimulate heavy spawning. 3. Fertilization should be started in the brood ponds at the time of stocking and continued until frost in the fall (see Fertilization, page 37). [351 4. Feeding should be started in the brood ponds at the time of stocking and continued through the summer at the rate of 6 pounds per 0.1 acre. Either soybean meal or cake or a mixture of 50 per cent poultry laying mash and 50 per cent hog supplement can be used as a food. (See page 5. Immediately upon stocking the brood fish, spawning mats should be added to the brood pond at the rate of 4 to 8 per 0.1 acre. 6. Examine the mats at least once, and preferably twice each day. When eggs are found (see Figure 18) the mats are removed and replaced with new mats. 7. The mats bearing eggs should be moved to hatching tanks or troughs. 8. When the young fry are three or more days old, they are ready to be stocked. 9. The rearing pond should be filled just 1 week prior to stocking to prevent an accumulation of aquatic insects that are predators on young fish. 10. Lower the water in the hatching tank or trough and remove goldfish either with a fine net or by carefully dipping them out with the remaining water. 11. Stock fry in rearing ponds at the desired rate. 12. Fertilization of the rearing pond should be begun immediately after it is filled and should be continued until the pond is drained or until the first frost. (See Fertilization, page 37 for rates and frequency.) 13. Feeding according to the selected program (rates I, II, or III, Table 5) should be begun immediately after the rearing pond is stocked and be continued until the pond is drained. The feeding can be regulated when shown necessary by sampling with a seine to determine whether or not food is being used. If food is not being utilized, the feeding rate should be reduced; if the minnows are not growing at a satisfactory rate it should be increased. 14. The crop of fish can be partially harvested by seining after some of the minnows are of salable size. The large minnows to be removed can be separated by the use of fish graders (page 66). 15. When the pond is drained it should be allowed to remain dry or should be partially refilled and poisoned (page 65) to kill stray fish that remain. 16. When a rearing pond is drained in the summer (June- 39.) [36] September 15), followed in the be remembered spring and that late summer. it can be restocked using the same procedures spring if eggs are available. However, it should that the peak of egg laying occurs early in the large numbers of young will not be available in GENERAL GOLDFISH HATCHERY PROCEDURES Fertilization The production of goldfish in unfertilized ponds and without feeding is not profitable since the amount of food in such waters is small. Commercial fertilizers will increase the production of microscopic plants and animals (plankton) upon which the goldfish feed. While it is most profitable to raise goldfish with fertilization plus the use of supplemental feeds, fertilization alone will produce about 900 pounds of goldfish per acre per year. Fertilizers, if properly used, will prevent weed growths that hinder draining operations and utilization of feeds by the fish. When the water has a dense plankton growth, underwater weeds are shaded out and will die. Fertilizers do not greatly increase food production for fish in ponds that remain muddy for long periods of time nor where there is constantly a very heavy flow of water. Since microscopic plants utilize the fertilizer materials only in the presence of light, it is essential for highest production that the water supply remain free of mud so that the light can penetrate the water and promote growth. Fertilizer and fish foods are lost in water flowing from ponds. The inlet valve usually should be regulated so that the pond remains full but does not overflow. Kinds Fertilizer /a Use. The fertilizers normally used in fish ponds (6) are satisfactory for use in minnow ponds. Experiments have shown that a fertilizer containing 8 per cent available nitrogen, 8 per cent available P20 5 and 2 per cent available K20 produces plankton most economically in this region. In some areas an 8-8-2 commercial fertilizer is available especially for use in ponds. Where an 8-8-2 is not available, equally good results can be obtained with 6-8-4 if sufficient ammonium nitrate or nitrate of soda is added to bring the nitrogen content up to 8 per cent. If neither 8-8-2 nor 6-8-4 is available, a readily available fertilizer may be purchased and the ratio adjusted with additional nitrogen and superphospate. [.37 ] Rate o Fertilization pen Acre. Minnow ponds should receive one of the following amounts of fertilizers per acre at each application: 1. 200 pounds of 8-8-2 or 2. 200 pounds of 6-8-4, plus 20 pounds of nitrate of soda or 3. 200 pounds plus 10 pounds or 4. any mixture 16 pounds 16 pounds 4 pounds of 6-8-4, of ammonium nitrate that will available available available give approximately nitrogen P20~ (phosphoric acid) K 20 (potassium) Frequency Gad Method j Application. The first application of the selected fertilizer mixture should be made 2 to 4 weeks before the brood fish are added in Method I (page 29) or as soon as the pond is filled. In Methods II (page 30) and III (page 34) fertilization should be started when the rearing ponds are filled. The next two applications should be made at 2-week intervals, and subsequent applications at 3- or 4-week intervals, so that the pond will remain highly colored with the tiny plants upon which goldfish feed. For highest production the food supply must be maintained by periodic fertilization. A total of 13 or 14 applications should be used each year. Fertilization should be discontinued in the fall at the advent of the first frost. The fertilizer should be broadcast from the bank into the shallow areas of the pond. Since the plant nutrients go rapidly into solution and wind and wave action usually distribute them adequately, it is not necessary to broadcast the fertilizer over the entire pond. Supplemental Feeding The highest production of goldfish has been obtained as a result of daily supplemental feeding in addition to fertilization. Numerous concentrates including wheat shorts, low-grade wheat flour, rolled oats, cornmeal, poultry laying mash, hog supplement, cottonseed meal, and soybean meal are frequently used. Stomach [38] analyses and field observations indicate that goldfish consume these supplemental feeds quite readily. In addition, those materials not.utilized directly as food act as organic fertilizers and increase plankton production considerably: Also, Swingle (4) indicated that organic materials increased fish production when used in combination with inorganic fertilizers by supplying additional carbon dioxide which is believed to be an important limiting factor on plankton production in recently filled ponds. Experiments conducted at this Station to date indicate that most efficient goldfish production is obtained from feeds having a protein content of from 30 to 40 per cent (Tables 3 and 4). Since there was little difference in the cost of the feeds used in this experiment, the use of the two materials that gave the highest production was obviously most profitable. Feeds for goldfish production listed in order of decreasing value are: 1. Mixture (50 pounds hog supplement, and 50 pounds poultry laying mash). 2. Soybean meal or cake. 3. Peanut meal. No significant difference in gold4. Poultry laying mash fish production from these feeds. Wheat shorts Select the feed with the lowest Red dog flour cost. Cottonseed meal TABLE 3. PRODUCTION OF OOLDFISH ATTAINED IN MENTAL FEEDS 161 DAYS BY USE OF SUPPLE- Treatments Goldfish production per acre Due to suppleTotal mental feeding pounds pounds Feed required to produce a pound of goldfish pounds 283.6 Fertilizer only wheat shorts Fert. 5.09 752.5 1,036.1 (17% protein) Fert. ± poultry laying 5.85 654.1 937.7 mash (20% protein) poultry laying Fert. mash + hog supple3.35 1,142.5 1,426.1 ment (30% protein) Fert. ± soybean meal 3.81 1,005.1 1,288.7 (41% protein) 1 Ponds stocked at rate of 26,000 goldfish per acre; fertilizer treatment, six applications of 200 pounds each of 8-8-2 per acre; supplemental feed, 3,828 pounds per acre. 2 Average results of two experiments run at different times. + + [39] TABLE 4. PRODUCTION OF GOLDFISH ATTAINED IN 175 DAYS BY THE USE OF SUPPLEMENTAL FEEDS Goldfish production per acre Treatments 1 Feed required to produce a Total Due to supplemental feeding pound of goldfish Pounds Pounds Pounds Fert. only 305.9 Fert. + wheat shorts (17% protein) 848.9 543.0 6.27 Fert. + cottonseed meal (36% protein) 890.9 585.0 5.82 Fert. + red dog flour (18% protein) 906.5 600.6 5.67 Fert. poultry laying mash (20%0 protein) 1,127.5 821.6 4.14 1 Ponds stocked at the rate of 26,000 per acre. Fertilizer treatment, four applications of 200 pounds each of 8-8-2 per acre; supplemental feed, 3,406 pounds per acre. 2Average of three replications. + It should be noted that although the cost of producing a pound of goldfish was cheapest where soybean meal was used, the highest poundage of goldfish per acre was obtained with a mixture of laying mash and hog supplement. Method the materials used in supplemental feeding should be fed daily at about the same hour and at the same location. After several days the fish become accustomed to regular feeding periods and congregate near the areas where they are fed much the same as do chickens and hogs. It is not necessary to mix water with feeds. The dry materials are usually thrown by hand into shallow water along one side of the pond much the same as in fertilization. Daily rate of feeding per acre. Supplemental feeding rates for young goldfish in rearing ponds (Table 5) appear to be satisfactory where there is little or no overflow of water. Recently hatched goldfish fry are quite small and, therefore, need only small quantities of supplemental feed in addition to the tiny plants and animals upon which they normally feed. Although many hatcherymen feed recently hatched fry every 2 to 3 hours for the first several days, such frequent feeding is not necessary since the young fish have abundant quantities of nat[40] 4 Applying Supplemental Feeds. For best results TABLE 5. FEEDING SCHEDULE FOR RATES I, II, AND III Age of goldfish in months Rate I Pounds of feed per acre per day Rate II Rate III pounds 10 10 20 20 20 20 20 20 20 pounds 10 10 30 30 30 30 30 30 80 pounds 0-1 (Apr.) 1-2 (May) 2-3 (June) 3-4 (July) 4-5 (Aug.) 5-6 (Sept.) 6-7 (Oct.) 7-8 (Nov.) 8-9 (Dec.) Fish production per acre 10 10 10 10 10 10 10 10 10 from fertilization + feed 1,800 lb. 2,100 lb. 2,250 lb. ural food present in fertilized ponds. A higher rate of feeding is obviously required as the minnows increase in size. The rates of feeding shown in Table 5 can be fed safely in shallow ponds with no danger of fish being killed. Higher rates of feeding can be used. This Station has fed 50 pounds of feed per acre per day safely in shallow ponds with no overflow water without killing fish; commercial producers occasionally use up to 100 pounds of feed per acre per day where water is available to flush ponds in event of low oxygen. In hot weather, ponds should be inspected frequently where heavier rates of feeding than those listed are used since the decomposition of feces, uneaten food, and dead plankton organisms may cause the supply of oxygen to become dangerously low. This condition is more apt to occur during long periods of cloudy weather when little oxygen is produced by the microscopic plants. When fish are found in distress from lack of oxygen, flushing the pond with fresh water should be sufficient to relieve this condition. Goldfish, although apparently requiring as much oxygen as other minnows, can stand a low oxygen concentration for short periods because of their ability to gulp air at the surface of the water. This characteristic makes possible supplemental feeding to attain high production of this species. The prospective minnow hatchery operator would do well to study Table 6 before deciding upon a feed or feeding rate to use. The method of producing minnows at the lowest rate per pound on a thousand fish is not necessarily the most profitable. Since the margin between cost of production and sales price is great even when the more expensive feeds and higher feeding rates [ 41] TABLE 6. THE EFFECTS OF VARIOUS RATES OF FEEDING PLUS FERTILIZATION THE PRODUCTION OF GOLDFISH IN 255 DAYS' ON Treatment Fertilizer, 2,600 lbs. 8-8-2 (applied in 13 applications) Fertilizer + 3,460 lbs. poultry laying mash' Fertilizer + 2,530 lbs. soybean meal' Pounds feed per pound gain Cost per pound of goldfish Pounds of goldfish per acre $ .055 4.9 :3.2 .143 .086 996.8 1,703.5 1,795.2 Fertilizer + 4,470 lbs. soybean meal' Fertilizer + 6,410 lbs. soybean meal' 4.1 5.2 .111 .138 2,090.3 2,234.6 'Experiments started April 4 and discontinued December 14. 2 Approximately 2,600 pounds of 8-8-2 per acre applied in 13 applications in each experiment. are used, the hatcheryman should be interested in the method that will produce the highest number of a given size minnow. By referring to Table 6 it may be seen that fertilizer alone produced 996.8 pounds of goldfish at a cost of 5.5 cents per pound or $54.92; while fertilizer plus 6,410 pounds of soybean meal produced 2,234.6 pounds of minnows at a cost of 13.8 cents per pound or $308.37. Assuming a weight of 8 pounds per thousand fish, which is the maximum for medium grade goldfish listed on page 43, and a sales price of $20.00 per thousand, it may be seen that there was $2,492.00 worth of goldfish produced in the pond that received fertilizer only, and $5,166.00 worth of goldfish produced in the one to which soybean meal had been added. The difference in return between the two ponds after deducting fertilizer and feed costs was $2,421.00 with only the additional expense of adding feed daily to the more profitable pond. Draining and Grading When only a small portion of the minnows present are to be sold immediately, the pond can be seined or trapped. However, draining is the only satisfactory method for harvesting the entire crop. Before a pond is drained, there must be facilities to haul, grade, hold and dispose of the minnows harvested. When the minnows are needed, the pond can be partially drained and the minnows concentrated in either the catch basin or holding pool. If the minnows are concentrated for an hour [42] mot(re, fresh wxater should he passed through thte catch lbasic. Nish concen trated in this moanner tcan 1)e r('tim) ('( quite readix wxith iasmall mililoxx scitl( or dip net and transferred to tanks or drums of water., 'I'h fish tan 1be coit ted and gradled for size wxhen harx (sted or held ungraded in holding pens or tanks. If the tninlo\xxl are ini Poor COnd(itionl as the restilt of harx estintg, they shotuld lhe held in tanks for 12 to 24 hours to allowc the n e ttod oxwt m h h c fish etor : .1 . Jc FIG. 21. Fish may be graded and han dlitong \innw Calt he effeetix dx tth gradled to size wxith itiettattital fish graders (page 66). Thee inax Also~ he gradedl and(coiti tedl Sittittitatteotislx On ia tdl)It (It ore 21) xwith a rim arolund the edge to th fib h counted fish may dropped into pails of 1 wex('lt floppin g off: slots at thet~corners allowx the fish to he dropped ito bttekets of wxater beiteath the tab le as thex are tot itlt((l. The sit rface of the talble mnuist he made of smrooth mnateri al su ch as glass or lit lolettnh atild shotuld( hax e a scale gradutatedI int inches pain tedl on it, to facilitate sortinigtlte minnoxx s ito the size groups showx i "iable 7. Whenh the sortit g table is wxet, it (lotes not injure the fish and( the per sont graIino . can ('asil\ (20tt and( grade the fish atld theni drop themt thronogh the appropriate slot in to a tanl of xxater. U stallxitt tot tintg fish, it is easier and~ faster to toltlet them in grottps of fix c thain sitnglx TABLE17. COMMXON1. ACCEPTED I'H) (I 5)5 nE I ()I I 11 counted an sorting tables surfaced with linoleum, alu minum, ar plate glass. Slots are left in each corner so that the Grade L.&ngth peur thousand Smll I -2 :*4 to 2y4 Mcim2 1.org& GEstra ILarge -3 8 - -4 I and [j4)3] (.1. 04 to H 8 to 17 17 and oos er Each group may be counted as one and when 100 is reached, a total of 500 fish has been counted. Where large quantities of fish are being handled, weighing is the quickest method of approximating the number. Find the average weight per thousand of the fish that are to be estimated by counting and weighing a portion, approximately 5,000 to 10,000 depending upon the total number involved. The remainder of the minnows can then be weighed and the average weight per thousand divided into the total weight of the uncounted minnows to give the number of minnows weighed. Transportation Hatcherymen who produce large quantities of minnows and whose retail walk-in trade is small, usually 'sell at wholesale prices to bait dealers and fishing camps. This necessitates transporting the minnows distances sometimes as great as a thousand miles. Large numbers of minnows are usually transported in specially constructed tank trucks; small numbers are sometimes shipped in cans via tank trucks, or via railway express. Regardless of the method used, certain precautions should be taken to insure delivery of a high percentage of lively minnows. Since the condition of the minnows at harvest is an important factor in the success with which they may be transported, they are usually "hardened" before the rearing ponds are drained. Hardening is accomplished by reducing the feeding rate for a period of 3 to 4 weeks before draining the ponds. This results in a slight loss in weight, but produces a tougher minnow. Hardening is especially important for minnow crops that are to be harvested when less than one year old. After the ponds are drained, the minnows should be held without food in tanks or cages (see Figure 12) for 24 to 48 hours to allow them to pass body wastes that would otherwise foul the shipping water. If, at the end of this time the fish appear to be in poor condition, they should be returned to a pond to recover. Although minnows can be hauled in containers such as milk cans or drums, specially constructed tanks are more suitable for trips of more than 4 to 8 hours duration (Figure 22). Tanks of this type also permit larger numbers of minnows to be transported for short periods of time than could be hauled in cans or drums. Tank trucks of various designs are used successfully by bait dealers throughout the country. Probably the more satisfactory ones incorporate either a water filter and spray system, [44] FIGURE 22. A 200-gallon trans.port tank may oc constructed of stainless steel or aluminum. The baffle is welded to the removable lid so that it will not interfere with netting the fish. The truck also carries a tank of compressed oxygen and an oxygen regulator connected by rubber tubing to the aerator stones lying under water in the tank. at sx stein of aeratill g the wxater b)\ passnim o\\ gell throlligh it, or a co)mbinlationl of the twxo. In the filter and spray sv stemi the water is remtov ed from the b ottomi of the tank b\ a small centrifuigal plumtp andl pumpedl throgh a filter contaji lti gCheese Cloth or oth er fidte material. Ilu wxater thus cleansedl of solid wxastes is spra\ ed lhack in to the tank for aeratioin. The spray sihould not fall (lirectix on the surface of the wXater xx11(1 transportin g goldlen shin1(rs ( page 57) In tan ks where wxater circulatioi is not emiploy ((I. aeration can be effected bx lnbllbng o\\ (gen through the xxater. 1'1 c o~x geit nrax be in pure form or it max\ be atniosphicric ox\ en. IAtnspheric oxx g1en is pi mped into the wxater by a com mn air coinpressor of a suitab~le size, whlile pore oxx gen may he purchased in ;3,000) to 6,000 liter cx ildcrs iii der pressu re. Ini either form the oXx gel shou ld be releasedI into the wxater thirough c arl ori idmn aerator ston es that break it oip iiito fine hbbbles exposinig more surface and greatlx increasili g its rate of absorption into the wxater. Small xaixes, tees, rubb~ler tin ili aind( aerato r stones F igiure 23 ) miaN be pu1rchlasedl from nitaim of the athlariulll slippYcoii pai ies xwh ose adx ertiseni eiits appear ini th ic~tlari ull trade magazimes. The aerator stones should be splacedl at ii iterv als of 2 to 3 feet alng the bottom (If the tan k to facilitate complete [ 45]1 Ir FIGURE 23. Shown here is the equipment far aeration of fish tanks with compressed oxygen. Lett: Therapeutic type at oxygen regulator that con be set to release from 0.5 to 15 liters of oxygen per minute from the compressed oxygen cylinder. This is usually set to deliver between 0.5 to 3 liters per minute during transportation of fish. Right: Type of aquarium valve (top left) placed in the line to each aerator stone to regulate amount of oxygen each releases; aquarium tees (top right) used to connect several aerator stones; corborundum aerator stones (bottom) which break up oxygen into fine bubbles. aeration of the wvater. A xalxve at each stonie is nccessarx to reguilate the ainotnt of ox'. geni that passes thro011gh it, a la rge anin t is wastefuli sitlce it does riot b ecomne xx-]ll- d11 x i ssolx ed. lIn addition to tihe xaix es and tees, an ox\ get r('gullator simnilar to the oine int igu~lre 2) mulst lhe u sedl to control the tremnous pressurte of the bottled gas. Thie ty pe uisedl b\ hospitals for therapeu tic u se is satisfactorx and fair]' in cx 1 ellsix e. I noler nlormal utsage the 3,OO() liter cx hiider wxill last 36 houirs an d the 6.000) liter one 72 houtrs at the approximate cost of tellt cen ts an hour. \ Iitllioxs wxithstand tran spolrtationi lest whielt the wxater tenmp)eratuire is approximlately 60t to TO F. Undtoer this cot (ition goldifish oftentCall he trat t5ported for short distan ces at tile rate of 2 p)oundics per gallonl of wxater. With (xperici ice, tihe lle\x hatcher m~an shoulcld learn the ititmbers of fish that lhe itax safekx tranlsport und~er differen t condiitiot s wxitht ihis particular cyiintent. lIn shipping titilioxxs x ia railxx a, exptress, the shippjer assutimes the miajor respoinsibility for thle miniltoxxs reaching the coinsigliee ini good conditionl. Thle express comlpal\ ihas no0 rigidl requtiremnts for shlippinig minnlowxs howxev.er, it h as some suggestionos b)ased 011 experienice that should b~e toliloxv cc. [ 461 1iiX ilardiX lllililoX stch as goldIfish si lot iid b~e sippiedL and theX' sh)ouIld he ill (goodl conditioni andc free' froml ti11ugus. MIinniowxs that are to ie sipped shulud ilaX e b~eenI held in tanks for at least 24 hou rs after renmo al frontothe pond1( to perm it the fish to oX ercom~e sihoc(k atid to p~ass wXaste p)rodlucts that Xoul I(It fool shppn \\ater. Thecse minnowII)Xs then call e safeix shipdi sitippinig precautionts are followxed. Th sippin110g conttainers miaX he of cariots sin(5 and sh apes le 5 buHt shoul h11 a larke diameter so th at a large Xwater siVtace aXe I is exposedl to the air. '1he XXater shotuld I e 2 or :3 in cihes )loX tihe shouiler of tile conitainter it a shold~er is presenit or snlhiietl fXIabelowx tie lid s(o r that tihe fish are not hull11eted again st it. The lid should he perforated and inset beloXw the top) of tie cati 5( that ice max be placed Onl top) of it to cool tile XVater ill transit. Smiall ojpenigs shouIldl be pro idied int the side of thte can at the desiredi XXatcr lev el to (drain emcess water caused front titeltitig ice and retillitig the can. A sihipp~ing container conisid( eredt~ idt'al for raiiX\ x press is sh)oXn in Ftligure 24t and (oine _______ I \ 2 -. 4II 21'- FIG. 24. Type of shipping container considered satisfactory for shipment of minnows by railway express. The recessed, perforated lid allows use of ice as illustrated. FIG. 25. Type of container devised and used by the Clark's Minnow Hatchery, Decatur, Ala., for shipping minnows by express. I, 1 used by a large minnow producer in Figure 25. Containers should be cleaned and inspected before each shipment to see that they are in good condition and free from leaks. Shown below is the number of goldfish railway express considers safe to be shipped in a 10 gallon container, from October 1 to March 1: Grades Total length Inches Goldfish per 10-gallon container Number 250 - 450 150- 250 50- 150 Small Medium Large 11/2 inches 21/2 - 31/2 inches 31/2 -41/2 inches -21/2 It is desirable to reduce the number 30 per cent from March 1 to October 1 as less fish can be safely transported in warm weather. In several other countries experimental work has been conducted to determine a method whereby fish can be shipped in sealed containers (1), (3), (8). Vaas used war surplus 5-gallon water cans which had been fitted with two tubes opening in the top of the can. These tubes were used to fill the cans with oxygen under pressure. The can was filled with water in which dibasic sodium phosphate (Na 2HPO 4) had been added to absorb the CO 2 . The fish were then added and the cans closed. Oxygen was forced through one of the tubes, water being allowed to pass out of the other tube. When approximately one-fourth of the water had been replaced with pure oxygen the tubes were closed. The cans were shipped laying on their sides in order to have the largest water surface exposed to the oxygen. The advantage of this method is that no attention is required while the minnows are in shipment. No experiments have been conducted on this method of transport with native minnows. FATHEAD PRODUCTION The fathead is a small slender minnow found naturally in many streams in the northern part of the United States. Although it seldom grows to a length of more than 31/2 inches, there is a heavy demand for them in the spring of the year, especially for crappie fishing. The larger sizes are used for bass fishing and are preferred by some fishermen to either goldfish or shiners. Fatheads can be raised in ponds and, next to goldfish are the 148] most desirable commercial minnow. However, they cannot be easily handled in hot weather and are relatively short-lived. Selection oa Brood Stock Fatheads may reproduce when the males are approximately 2 inches and the females 11 inches in length; however, brood stock over 21/ inches are desirable since they usually give better results. It should not be difficult to obtain minnows of this size for brood stock since most fatheads sold for bait are at least this large. The brood stock should be free of external parasites and in good condition; consequently, the initial brood stock should be purchased from a reliable dealer who operates a parasite-free hatchery (see Parasites, page 58). After the initial year, brood stock should be selected from the previous year's production. Care of Brood Stock When a pond is drained, the brood stock should be selected from the larger fish. Depending upon the time of draining, these can be restocked immediately or held in holding ponds. If they are held in holding ponds, they should be fed soybean meal or one of the two mixtures shown on page 39. They should be removed from holding ponds and stocked before the water reaches 62 ° F. as they will lay eggs even when held at the rate of 120,000 per acre. Stocking Fatheads should be stocked between February 15 and May 1 at the rate of 1,000 per acre. The sexes should be approximately equal. Cold waves following warm weather will result in loss of some eggs but this apparently does not materially reduce production. TABLE 8. THE EFFECTS OF VARIOUS STOCKING RATES FATHEADS PRODUCED PER ACRE' ON THE NUMBERS OF Stocking rate per acre Number Average production per acre Number 500 1,000 2,000 10,000 1 140,000 168,000 283,000 94,000 Fertilization only until fall. Ponds stocked February and March: [49] Sexing Tli( noades call he (Iistinits~1ilU'd from the femtales (11161wti the t 1 )rcles dlarkerlor,)~f the pr se tet of tube pad~ ont the lhack (\tcnin(h2 fromt tlte head to attc. the mulles arec alwxav s the dlorsal fin. Ili fish of the 'amei larger thant females. hi )e('(i I season n th( 11i5se, and(it by) their Spawning Habits the \t .\ttln-rit Alabamta, spaxxttin 1(gitts if] the spriI .i xx1ltc w\ ttor temtperatutre reaches 60 to 62 F. and uiuitiutes throug hout the sltituict. Spaxv iitg has lecen recordedl as late as October 1. the ('aa5 are laidl ilk slhallo\\ watter on the underside of rocks, the fatheadi xill o ') I IO\ (\er, hoardIs, antd larme roots ti :I I I ; ni ( v \\ ttc ;l i o It i i f I I - 'trtu ( I ( I I I I ill d(III -iru 1' ya.. } wt~ FIGURE 26. bricks oab, Foth cod eggs are taid orn the und,.r side of firm rock. hcoards. and similar materials. objl. t., uach as FIG. 27. The male fathead minnow sweeps out a nesting place ur nderneath a rock on the pond bottom. \\ ltti all itestit . mtateial xxas IpltIVscl rIxx t ovx f( rot it apond '(.s ri ule. laidi ott the i itderside of leax es. ard clax. sit all sticks, ail h( 'I'hte ale utsuiall x prepares the nest hx citcarilig the utuldcirside of rocks amod hoards iFigrie -I ). lThe eggs are thten dlepositedl 1) the t ciiiales oin these' si irfaces. Sex cira1 fen tales not pireseit. ofteit lay together, forintg i [51] lIN cr of egs that often coy ers :361 lare incehes. 11we miales teed~ sqi the constanitly-, ruling~i t. the eggs)~ xvitli th pdtat l aiest is present on the top)of the head. This action l)x the male is appareti n ecessary- since on- sev eral occasions 'xvhere the e("gs xx eve remox ed and~ incublatedl wXithout the male, a poor hatcht X olbtainled. Afvas ter spawning actix itN , the males begin to die and NX eon~tinuow ill to (lie throughout the suimmter. Some females (lie also butt in smaller numb1Hlers th an the males. Management The p)ond should be prepared for fatheads by plaig flat rocks or spawXning h~oardls ( Figure 28 ) in the shallo~xXXater (1 toot deep). Spawning boards are used to suipplem t the rocks andl ien consiist of 1 x"4-inceh boards 4 to 12 feet lotng, staked about 3 inichies abov e the poll(1 bottomi. The fertili'zatioii program should be started 2 wXeeks before stoceki] ig and coti ii ed throughout the slitmimier. W'here feedingi is started in the suiiiier. reproduiction is so) heaX N that it is imOpossible to raise all ot the fatheads to a marketable size witliout tratisterritig part of them) to other pond(s. ;otiseyutititl\ feeditig should n ot be started unt til the wXater h as coouledh suiicliitix to p~rev ent spaxx ii]ig. (O(ctober 1 to 15 at Atuuirni Alabama.) Feedliig shoutld be startedl iii tbe fall, at the rate of 20) pottiids s Ti f> A FIGURE 28. Spawning boards for fathead minnows are staked in the pond where the water is about 1' deep. The boards are 1" x 4", 10'-0" long, and usually are placed not over 6" above the pond bottom. [51 ] TABLE 9. THE EFFECT OF VARIOUS RATES OF FEEDING ON FATHEAD PRODUCTION IN FERTILIZED PONDS 1 Treatments Feeding period fertlin overnly Total production Pounds Fertilizer only Fertilizer + 2,750 lbs. poultry laying mash Fertilizer + 2,900 lbs. soybean cake Nov. 1 - Feb. 18 Oct. 1 - Feb. 25 Oct. 1- Apr. 4 360.4 715.5 1,042.8 Pounds 148.0 508.4 863.5 1,190.8 Fertilizer + 3,760 lbs. soybean cake 1Fertilized Feb. 3, to Sept. 8, with 1,600 pounds 6-8-4 and 40 pounds nitrate of soda. per acre per day. The same rate may be continued until harvest or may be increased in January or February to 40 pounds per acre per day if the minnows have not reached marketable size. Since fatheads will utilize the same supplemental feeds as goldfish, those shown on page 39 can be used. Stocking with 1,000 adults will give an average production of 168,000 fatheads per acre per year (Table 8). With fertilization plus heavy feeding during the period October to April, a weight of approximately 1,200 pounds can be expected (Table 9) and the minnows will average approximately 2.4 inches in length. As this was the largest number of usable size fatheads that could be produced per acre at Auburn, it was not advantageous to stock brood fish at rates that produced young in greater quantity. If the pond is overstocked or higher reproduction than usual is attained, the fish must be fed at a higher rate or part of the minnows removed and transferred to new ponds. They should be stocked in these ponds at the rate of 100,000 to 150,000 per acre. When the rearing ponds are drained, the larger fatheads, usually 85 per cent of the total crop, should be held and sold. The undersized minnows should be retained and fed one of the feeds shown on page 39. The small minnows should be transferred in January or February so that they will reach marketable size before spawning. The transfer ponds should be drained when the first eggs appear or when the water temperature approaches 600 to 62 ° F. When minnows one inch or more in length are transferred an [52] average survival of 75 per cent can be expected: the smaller the minnows the lower is the percentage survival. Therefore, if possible all minnows should be over 1 inch in length before being transferred to rearing ponds. The procedure for raising fatheads by the fertilization-winter feeding method is as follows: 1. About 2 weeks before the anticipated spawning date, select ponds not over 0.5 acre in size and less than 5 feet deep. Place stones or spawning boards in water not over 2 feet deep. 2. Immediately upon filling the ponds, fertilization should be started at the rate of 200 pounds per acre per application (see page 38). The second and third applications should follow at 2-week intervals and subsequent applications should be made at 3- or 4-week intervals until the first frost. 3. When the water temperature approaches 600 to 62 ° F. (March 20 to April 15 at Auburn, Alabama) stock ponds with adult fatheads at the rate of 1,000 per acre, using approximately equal numbers of each sex. 4. Feeding should begin in the fall when the water is sufficiently cool to prevent further spawning. (October 1 to October 15 at Auburn, Alabama.) 5. Feed any of the suitable feeds shown on page 39 at the rate of 20 pounds per acre per day. The rate may be increased to 40 pounds per acre per day in January or February if most of the minnows have not reached a marketable size. 6. Rearing ponds are usually drained during the period January 1 to March 1. At this time 85 per cent of the minnows should be of salable size. 7. Those minnows too small to sell can be restocked at the rate of 100,000 per acre and grown to usable size provided there is at least one month between the time of stocking and the normal spawning period (water temperature 600 to 62 F. about March 20-25 at Auburn, Alabama). 8. The fish in the transfer ponds should be fed at the rate of 20 pounds soybean meal or cake per acre per day. This rate may be adjusted to attain the desired size minnow by harvest time. 9. All of these ponds should be drained when spawning activity is noticed and the usable minnows concentrated for disposal. Fatheads are usually not sold as bait during the period June to October because of the increased mortality from handling and transportation in warm weather. [583] Draining aGza Grading The draining procedure for fatheads is the same as for goldfish (page 42); however the fatheads are not as hardy as goldfish, and must be handled with greater speed and care. Since fatheads cannot stand crowding in tanks or buckets, the use of oxygen is recommended when holding or transporting them (Figure 22). Fatheads are graded much the same as goldfish but instead of several size groups they are separated into those large enough and those too small for bait. The size usually used for bait is 2 inches or larger but may be smaller in some localities. The smaller minnows are discarded or restocked and allowed to reach marketable size. In minnow ponds that are in production from spring to spring, considerable difficulty is usually experienced with tadpoles. When the fathead ponds are drained in the spring only the larger bullfrog tadpole remains. These are of such size that they can be separated from the minnows with a 5/8- or 3 /4-inch grader (see page 66). Transportation Ordinarily, fatheads are not shipped by railway express since they are not as hardy as goldfish and do not stand shipment as well. In transporting fatheads the same equipment can be used that is used for transporting goldfish. However, fatheads cannot be loaded as heavily as goldfish and greater precaution is necessary to insure safe arrival. In Alabama the transportation of fatheads is confined to the winter and spring since they may not be handled safely in summer. GOLDEN SHINER PRODUCTION The golden shiner is found in lakes and sluggish waters throughout the United States east of the Rocky Mountains. It grows to a length of 10 to 12 inches. There is a heavy demand for shiners in some areas of the Southeast, especially Florida, where they are the preferred bass bait. The golden shiner can be raised in ponds but when compared with goldfish and fatheads it is the least desirable commercially. It is a soft minnow and even when handled under favorable conditions bruises easily and is subject to heavy fungus infection. In warm weather it cannot be handled at all without heavy losses. From experiments at this Station it does not appear that golden [541 shiners can be produced as intensively as goldfish but require an extensive type of culture. Selection a/ Brood Stock Golden shiners may reach sexual maturity when they are 31/ to 4 inches long. However, brood stock over 6 inches are desirable' and usually give the best results. Under similar conditions the females are usually larger than the males so that the brood stock should not be selected on the basis of size alone. The brood stock should be free of external parasites and in good condition; consequently, the initial stock should be purchased from a reliable dealer who operates a parasite-free hatchery or may be seined from natural waters. Regardless of where obtained, these fish should be held for a sufficient time to insure freedom from external parasites. (See Parasites and Disease of Bait Minnows, page 58). Following the initial year, brood stock should be selected from the previous year's production. Care aj Brood Stock The brood fish should be selected when a pond is drained, and depending on the date, can be restocked in brood-rearing ponds or placed in holding ponds. If the fish are placed in holding ponds, they can be fed soybean meal at a low rate not to exceed 5 pounds per acre per day. They should not be held crowded after the water exceeds 60° F. since heavy losses sometimes occur as the result of fungus infestation. Stocking Golden shiners can be stocked from March 1 to May 1 at the rate of 800 to 1,000 per acre. There is no known method of externally determining the sex of shiners. Spawning Habits The golden shiner spawns later in the spring than either the goldfish or fathead. At Auburn, Alabama, spawning begins when the water temperature reaches 68° F. and continues throughout the summer with as many as four distinct spawns in one pond. Under natural conditions the eggs are laid in shallow water on weeds, trash, and filamentous algae. No protection is given to the eggs or recently hatched fry by the parents. Management The ponds used for shiner production should be filled and the fertilization program started 2 weeks before stocking and con[55] tinued throughout the summer. Care should be taken to keep the ponds free of other species of fish; green sunfish, bluegills, and top minnows, are extremely detrimental in shiner ponds, reducing production severely. The pond surface should be sprayed with diesel fuel or kerosene (see page 61) at the time of stocking and one month later to control air-breathing aquatic insects that eat small fish. Additional spraying may be necessary for predaceous aquatic insects during the summer if seining indicates they are numerous. In experiments at this Station a kill from oxygen depletion has occurred in all ponds where shiners were fed in the summer. Consequently, in this region golden shiners should not be fed during this period. A low rate of feeding, not to exceed 10 pounds of soybean cake or meal per acre per day can be used in the winter without too much danger of loss from oxygen depletion. While feeding cannot be used in the summer, fertilization can be used safely to increase production when a pond is stocked properly. From 30,000 to 235,000 shiners weighing 375 to 600 pounds can be raised per acre per year. If 600 pounds per acre are produced, the maximum number that can be raised to an average length of 3 inches is 70,000 per acre. Where the procedures recommended below were followed, the average production was approximately 75,000 minnows and 500 pounds per acre. Of these minnows, 80 to 90 per cent were 3 inches or larger. Since the production rate of fatheads or goldfish is two to four times that of golden shiners from an equal pond area and bring virtually the same price per thousand, golden shiners are the least profitable to raise. The procedure for raising golden shiners is as follows: 1. Fill the pond with water about February 1 to 15. 2. Fertilize immediately and continue fertilization until fall as directed on page 38. 3. About March 1, spray the water surface with kerosene to kill predaceous water insects (see page 61). 4. Stock the pond with 800 to 1,000 brood golden shiners per acre between March 1 and May 1. 5. Since eggs are laid near the water surface, maintain a constant water level until after the eggs hatch. [56] 6. Check the pond at monthly intervals with a fine-mesh seine. If large numbers of predaceous insects are present, respray with kerosene as directed in step 3 above. 7. Drain ponds between December and February, and sort and sell minnows of suitable size. 8. Minnows too small to sell should be restocked in ponds at a rate not in excess of 50,000 per acre. Fertilize every 2 weeks (see page 38) and feed soybean cake at the rate of 10 pounds per acre per day. Drain the ponds and sell the minnows within 2 months or before they spawn. Draining and Grading The draining procedure for golden shiners is the same as for goldfish (page 42). Since golden shiners are not as hardy as either goldfish or fatheads they must be handled with speed and care. As shiners cannot be crowded, the use of oxygen is recommended in holding them. It is imperative that the container in which they are handled be covered to prevent loss from jumping. Golden shiners are graded in the same manner as goldfish but instead of several size groups they are separated into those large enough for bait and those too small. Only shiners 3 or more inches in length are used for bait. The smaller minnows are discarded or restocked and allowed to reach a marketable size. Tadpoles may cause considerable difficulty in shiner ponds; however, when the ponds are drained in the spring the tadpoles that remain can be removed with a fish grader having a 1/2- or %8-inch bar opening without injury to the shiners. Transportation The transportation of golden shiners is limited to the cooler months of the year. They are never shipped via railway express. When water sprays ordinarily used for goldfish transportation are applied directly on the water, shiners have a tendency to jump causing many injuries. This can be alleviated by baffling the spray so that it does not strike the water directly. For trips of 12 hours or less in duration, it is preferable to use oxygen alone (page 45). With this method, up to 7,500 shiners 4 to 5 inches in length can be hauled per 100 gallons of water without injury if the temperature is 650 F. or lower. [57 1 PARASITES aod DISEASES 4 BAIT MINNOWS lhcre are fluitti pa rasites and d(1s(1as8s that attack lbait minnfows hilt thiere is little itniormatiotn on the (\teit of iiiuirx Somne of the more important p)arasites atd d((i seases that call be easily rcco(rtH ieci are an chor parasites- fish l ie, grubs, fu i i s disease, Anchor Parasites The anichor parasite ( Lenea sp.) is fotitd ill mny ntuiral wXaters throuighou t the 1 11ited States and is probaihix tie" most ( (letritiilftil parasite present ini tilitiio hatcheries. 'Ilie adult femtale ( 'imure 291, which is monst r(ai fondo parasit izied 1 fish. resembles a smtall wh ite stick wXith a bulb11 attached at the (cud. Ihis 1) ll)as two c h egg sacs which canl b e readlily sep~aratedl. IThese parasites infest all commtioni iniiiws. I.ame fish. and( some tad(1poles. "There have beI iui sta ics Xwhetre th e in festationm Xas s(o hleaXX u th at the entire cro))p o i ioXX w lost. Thiis wXas particular ly Xas trite wXith shiniers and fatlieads sitice thiey didh n ot appear to lhe as t (sistatilt as (ithdfish. id (l ;) repor ts that alter 1 tt itntested, lit (goldfish showXXed signs ouf distress atild exhautstiont wXithi largec inflat areas on the sidle andi~ bactk. Wihere the inufestat ion Xwas ctd limiited to three to fiv e femiale parasites to at 2-itich gouldfish it did( not cause dleath, buit XXhere the itifestatiotn XXas 1t) 1.5 to per fish nitilti gohllfish (lied ili I( ton 2() dlaXs. \Iimha!"i )ti/(.d \v itli aiij(Iflf Ir,ua~iite, s latii mt linc wwde~ 1 FIGURE 29. The anchor parasite IL ,,j) is shown here attached to a goldfish minnow. The point of attachment usually is red and inflamed and often has the appearance of an ulcer. Insert: Close-up view of the female anchar parasite attached to a fish and showing two egg sacs. [ 58] as bait since there is a possibility that parasites may be introduced into regions where they did not previously occur. Anchor parasites will attach themselves to game fish, causing sores and inflamed areas at the point of attachment. These sores and inflamed areas render many hard sought gamefish unusable to the fisherman because of their obnoxious appearance. Control. There is no known treatment that will completely control anchor parasites on large numbers of minnows. Prevention must be practiced by obtaining fish for brood stock that are free of anchor parasites. When the brood fish are first obtained they should be inspected, and even if they appear to be free of anchor parasites they should be kept in a holding pond where the water temperature is 820 F. or above and checked at intervals for 16 to 18 days. If at the end of this period the fish appear to be free of anchor parasites they can be stocked. When brood fish are infested with anchor parasites, it is usually desirable to poison all fish and tadpoles in the hatchery (see page 64), and start over with parasite-free brood fish. Treatment of brood fish with potassium permanganate at weekly intervals is often resorted to, but will not eradicate this parasite. Fish Lice Fish lice (Argulus sp., Figure 30) may be found externally on most species of bait minnows. The extent of injury is unknown but where there are large numbers of fish lice in hatchery ponds some injury probably results. While there is no known treatment for large numbers of minnows, a small number may be treated by placing them in a 3 per cent salt solution for 10 minutes or until they show signs1 of distress. This solution can be prepared by dissolving common table salt in water at the} rate of one-quarter pound per gallon. Contaminated ponds may be treated by draining and allowing them to dry. If it is impos- sible to completely dry the ponds they may be sterilized with either hydrated lime (cal- with hydrated lime (caleither FIG. 30. The fish louse (Argulus sp.) isoften found inlarge numbers on bait minnows. [59] cium hydroxide) or chlorinated lime (bleaching powder). Since chlorinated lime is costly, it should only be used for tanks or small ponds. Hydrated lime is used by mixing it with water to form a milk that can be sprayed with an orchard type sprayer. The mixture is sprayed over the entire pond bottom giving especial attention to platforms, valves and drains. The mixture should be prepared fresh for each application as it loses strength rapidly when exposed to air. If chlorinated lime is to be used, the chemical should contain not less than 70 per cent available chlorine. This material may be used by broadcasting lightly over the moist pond bottom; better results will probably be obtained by partially refilling the pond to cover areas which will not dry out and broadcasting the chlorinated lime over the water surface at the rate of 60 pounds to each acre-foot of water. Grubs The black grub (Neascus spp.), yellow grub (Clinostomum marginatum), and the white grub of the liver (Posthodiplostomum minimum) may all be found in bait minnows. The extent to which these grubs injure fish is unknown; however, most fishermen object to purchasing diseased fish. These parasites are spread in ponds by fish-eating birds such as herons and kingfishes. In areas where such birds are numerous a high infestation may be expected. No trouble is experienced from grubs in hatcheries where aquatic birds are not found. Water Mold Water mold (Saprolegnia spp.) is a common fungus disease that appears on fish. It is similar in appearance to mold on bread and can be seen plainly when the fish are in water. Saprolegnia spp. is not usually the primary cause of trouble but generally follows injuries and conditions such as those caused by handling, crowding, or low oxygen. In shiner populations this fungus appears in epidemic proportions in ponds where there is low oxygen even when the fish have not been handled or have no visible injuries. It is more prevalent in warm water than in cold. Control. The dead and diseased fish should be removed from the ponds daily to prevent the production of spores for infection. Potassium permanganate at the rate of 2 p.p.m. is commonly used in hatcheries to treat entire ponds. Six pounds of potassium [60]1 permanganate crystals are required to give this concentration in one acre of water one foot deep and are applied by broadcasting them over the water surface. This treatment can be repeated daily if necessary. Where the minnows are confined in tanks a dip in 3 per cent salt solution for 10 minutes or until the minnows show distress is helpful. Fin Rot This infection is observed frequently in bait minnows where they are held in tanks or troughs. It is usually characterized by a white margin on the outer edge of the fin. As the disease progresses inward toward the base of the fin, the fin rays are left bare and frayed and the entire fin may rot away. Control. Since this disease is usually present when fish are confined to tanks, the fish can be treated with potassium permanganate (one-quarter teaspoonful potassium permanganate dissolved in 100 gallons of water), or a 3 per cent salt solution for 10 minutes. All fish that have the disease so far advanced that the fin rays are exposed should be removed. PESTS azd THEIR CONTROL Pests do not usually offer a serious problem unless they are extremely numerous. Since all of the pests listed below with the exception of muskrats and tadpoles will eat fish, the more numerous they are the lower the production of minnows. The more common pests and their controls are discussed below. Insects Some aquatic insects are predaceous upon small fish and other insects. The most troublesome kinds such as the back swimmer and water tiger are easily controlled with oils. Kerosene or diesel fuel will control air-breathing aquatic insects if applied at the rate of 2 to 4 gallons per acre. A garden sprinkler or spray can be used to apply the oil on the surface. Frogs Large frogs cause some loss by eating small minnows. Tadpoles of large frogs, principally Rana spp., consume large quantities of food and interfere with sorting and draining operations. In some ponds the weight of tadpoles has reached 2,000 pounds per acre. [ 61] Control. The only practical method for control of frogs is to fence the ponds with 1/4-inch mesh hardware cloth. The fence should be buried approximately 6 inches and extend 36 inches or more above the ground. Ponds should be fenced in the spring or early summer while they are drained and free from frogs or tadpoles. Where the ponds are not fenced the number of frogs and tadpoles can be reduced by shooting the adults and removing the eggs daily with a dip net. Crayfish Crayfish, although usable as bait, create a problem in minnow ponds since the burrowing forms tunnel through narrow dams causing leaks and thus lowering the water level. Considerable loss by predation is also caused during draining and sorting operations when the minnows are concentrated. Control. Burrowing forms of crayfish can be killed by placing 1 teaspoonful of lye in each burrow. When a pond is drained, crayfish at large in the pond can be controlled with chlorinated lime (see page 59). Muskrats Muskrats burrow through the dams in minnow hatcheries causing them to leak. Control. Muskrats can be controlled with either poison baits or traps. For poison baits strychnine sulfate is used as the poison and quartered mellow apples as bait. To poison an apple a match stem is inserted in the apple and then into the powdered strychnine. Enough strychnine to be poisonous to the muskrat will adhere to the match. This poison is then inserted in the previously punched hole. The poisoned apples are placed in the burrows. If there are sufficient muskrats present to make the furs worth harvesting they can be trapped with fish traps baited with an apple, or with steel traps placed in front of the burrow. Snakes Fish are an important item in the food of some snakes; it is therefore expected that they would cause some loss of fish. Control. Snakes can be controlled by shooting if marginal weeds and other hiding places around the pond are removed. [62] Turtles Snapping turtles and some other tx pes are knowx n to eat fish. Snapping turtles can lbest he controlled l)\ tlnlerwater traps (Figures 31 and :32). Both may also lbe controlled 1 shooting. { i~ d ii FIG. 31. A simple underwater trap for turtles may be canstructed af welded wire. The muzzle opening should be oval, and vertical slats (see arrow) should be cut in the sides and end to allow the escape of fish. FIG. 32. An inexpensive tilt-board trap is effective for capturing the basking types of turtles. A weight attached to the underside of the tilt-board (on left side of pivot rod in photo) resets the trap. The trap is placed so that the top is about 8' to 12' above surface of the water. II 4 j. 9 V . 46 - . . r~ tA 4 t [6331 Fish-Eating Birds Herons. There are several kinds of herons that frequent hatchery ponds. In this region the great blue heron, the little blue heron, and the green heron are prevalent. These birds are often present in large numbers and consume a number of fish. Where fish are concentrated in holding ponds these birds may practically eliminate the entire crop. Some herons also serve as the final host for grubs that infest minnows and distribute parasites from pond to pond. Although protected by federal law these birds are a nuisance around hatcheries. A hatcheryman is fortunate if the number that frequents his ponds is small. Some species of herons may be kept away by stringing wire or cord across the pond and attaching pieces of cloth or shiny tin-foil to it. King fishers. Like the herons these birds consume large quantities of fish and serve as the final host for the black grub that infests fish. They are also believed to be the cause of some obnoxious fish being present in minnow ponds. Although protected by law in some states, these birds are a nuisance around hatcheries and should be kept out wherever possible. ELIMINATION of UNDESIRABLE FISH POISONING It is important that all fish be removed from hatchery ponds before they are restocked since any remaining fish will seriously reduce production in the succeeding crop. Usually time does not allow these ponds to be completely dried, so that poisons must be used. The poisons recommended are powdered derris, powdered cube, or emulsifiable rotenone each containing at least 5 per cent rotenone. Any of these poisons used at the rate of 3 pounds for each acre-foot of water and thoroughly mixed with the water in the pond will kill most fish usually present in hatcheries if the water temperature is above 60 ° F. Where the pond is treated with chlorinated lime or hydrated lime as a disinfectant as recommended on page 59, it is not usually necessary to poison as the lime will kill the undesirable fish. Emulsifiable rotenone gives the best results and is the easiest to handle since it is a liquid and requires no mixing before application to the pond. The price of emulsifiable rotenone is 21/ times higher than that of powdered derris or cube which require preliminary mixing with water. Emulsifiable rotenone is the most [64] effective of the three in controlling top minnows when it is thoroughly stirred into the pond water. When the powdered forms are used very often some of the top minnows are not killed because it is difficult to mix the poison with the thin upper layer of water even when the pond is stirred by an outboard motor. The procedure for poisoning a pond is as follows. 1. Partially refill the pond so that all wet places are covered with water. 2. Carefully estimate the area and average depth of the water to be treated. 3. From the surface area and average depth find the amount of poison necessary in the table below. The figures in Table 10 represent ounces by weight if a powder is used, or fluid ounces if emulsifiable rotenone is used. TABLE 10. AMOUNT OF CUBE, DERRIS, OR EMULSIFIABLE ROTENONE TO KILL FISH IN PONDS OF VARIOUS AND DEPTHS REQUIRED Surface area in acres 3 Ounces Average depth of water in inches 6 9 12 15 Ounces 3 5 6 8 10 12 15 18 Ounces 4 8 9 11 15 18 22 27 Ounces 5 10 12 15 20 24 29 86 Ounces 6 12 15 18 24 30 36 45 18 Ounces 8 15 18 22 29 86 44 54 1/10 1/5 1/4 2/10 2/5 1/2 3/5 3/4 2 3 3 4 5 6 8 9 4. Weigh or measure the amount of poison required. If powdered derris or cube is used it should be mixed with a small amount of water to form a paste. Then the paste should be diluted with additional water sufficiently to permit even dispersion of the poison. The emulsifiable rotenone may be diluted with water before application. 5. Place an outboard motor mounted on a sawhorse in the pond. Gradually pour the diluted poison into the "prop wash" of motor, stirring until the poison is evenly distributed. By moving the motor the pond can be treated from several positions, giving more thorough coverage. This is desirable when the surface area of the pond treated is over 1/4acre. 6. After the pond is completely stirred, wait 24 to 48 hours or more, then drain it completely. If the hatchery drains directly [ 65] into streamns, it wxill be neeessarx to holdd this poisoned water for 2 weeks or to dlilute it xxith about fix times the \olnne of water e in the hateherv pond so that it is no( ]oi ecr toxic to fish before releasing it in~to the stream. This material is not poisonous to lix estock. 7. [he pond~ can then b~e completel refilled and( is readyx for use. Care shoulId be taken that higher coincentrationis of poison than those reeon ine ided are not usedi and( th at th e poison that remin s after dhailning is sufficientl dlx(iiited that it wxill not kill fish. MECHANICAL FISH GRADERS MIeehanical fish graders speed the gradiiig of ]iiiioxs without the dawitcr of mju rv encouni tered lihe fish are g~rad~ed across a tab~le. hTere are sexveral t\ pes of fish graders (Figure :33 ) but thex all grade fish lbx the xwidth of the bodx . The size of the gradler (distance b~etxween lbars )determtines wxhiech fish are retainied. To gradle fish pi operl\ there should b~e gradlers of xvarious sizes snethe fish x arx ini size from p~ond to po011(. The graders should lbe co ustri ite(1 xxith 1 16-inch chainges ini d1istante b~etxxeen bars in each size grader. The bars shouIld be made of staii less steel or aliuniiui allox of sufficient hardness to xxithstand~ bloxxs. For best serx ice the graders should float. There is uisuiallx enough boi ixanex iin the xxoodlen sidles to (10 this, hoxxex er. wxhere the gJraders will not float, cork can be nailed to the sides to increase the lhoix aiicx of the grader. FIGURE 33. Fish graders may be used to separate tadpoles and various sizes of minnows. They may be made of aluminum rods or similar material inserted into wood frames. Spacing between rods shown above are: left 3 16", center 7 16' and right 11 16" [i 6] With experience the hatcheryman will learn the size graders necessary to separate each grade of minnow. The graders may then be floated in a holding tank, or tub, and fish put in them in large enough numbers that they are badly crowded. Under these conditions those fish too small to be retained by the grader will quickly swim out into the tanks. If the fish that have escaped are to be resorted into smaller grades, they may then be run through another grader that will sort the next smaller grade, and so on. Gentle shaking of the grader by the hatcheryman will speed up the process. WEED CONTROL The growth of higher aquatic plants and certain types of filamentous algae in hatchery ponds should be discouraged since they reduce production. In ponds that have heavy growths of these plants production is reduced because of the incomplete recovery of fish on draining, and because the supplemental food is not completely utilized. In addition in some areas weeds harbor malarial mosquito larvae. Rooted aquatic plants do not normally present a problem in well managed minnow ponds except along the margins in water less than about 6 inches deep. However, these marginal growths and filamentous algae may become objectionable and in improperly fertilized hatcheries deep water forms may appear. The methods for controlling pond weeds in general are discussed under the following headings: submerged weeds, emergent weeds, marginal weeds, and filamentous algae. Submerged Weeds Submerged or underwater weeds usually have roots and stems and grow on the bottom, but do not usually grow to the surface of the water. However, Chara which is a submerged plant is an alga. Some examples of submerged weeds are Na/as, coontail, pondweeds (Potomogeton), and Elodea. Control. Since all green plants require sunlight to survive, its restriction prevents their growth. In ponds managed for the maximum production of minnows as outlined in the sections of fertilization and supplemental feeding in this circular, submerged vegetation does not become a problem. This is because in well[ 67] managed ponds dense growth or bloom of microscopic algae prevents sunlight from penetrating to the bottom in waters deeper than about 6 inches. However, care should be taken that fertilization be commenced immediately upon flooding the ponds as rooted plants may appear very quickly in clear water. During the first year a hatchery pond is in operation some delay might be experienced in obtaining a good plankton growth after fertilization is begun; in subsequent years the organic residue remaining in the pond will stimulate a bloom almost overnight with fertilization. If submerged vegetation becomes established there are several known methods of controlling it. Probably the best method for hatchery ponds that are drained at least once a year, is to spray the vegetation with sodium arsenite solution as soon as the pond is drained. Sodium arsenite containing 70 per cent arsenious acid should be purchased, mixed with equal parts of water, and sprayed directly on the plants. Enough spray solution should be used to completely cover the vegetation. The pond may be refilled 24 hours later. Care should be exercised in the use of sodium arsenite as it is toxic to livestock and is caustic to the skin. Emergent Plants anu Marginal Weeds Emergent plants are those plants that are rooted to the bottom but produce leaves and seed heads above the surface of the water. Some examples are pennywort, watershield, and water lily. Marginal weeds grow along the pond bank and in shallow water. Examples of these weeds are sedges, cattails, arrowhead, and pickerel weed. Control. These plants may be controlled by using a solution of 2,4-D in oil. One measuring cup (8 fluid ounces) of a 2,4-D ester (containing around 40 per cent acid) should be used to each 5 gallons of diesel oil. The ingredients should be thoroughly mixed and applied with a knapsack or low-pressure garden sprayer. The vegetation should be completely covered which takes an average of 100 gallons of spray per acre for most plants. If it rains immediately after the spray is applied retreatment will be necessary. The sprayers should be thoroughly cleaned before used for other purposes as these materials will kill most plants, including orchard trees. [ 68]1 Filamentous Algae Filamentous algae begins growth on the pond bottom or on submerged plants and trash. When growth is advanced they will float to the surface in mats sometimes covering the entire surface of the pond. Filamentous algae do not have roots, stems, or leaves but resemble a mass of green threads or hair. The hairlike strands may be straight or branched depending upon the type. Control. The forms that grow in the winter, principally Spirogyra in this region, usually disappear when the water begins to warm up. If they persist, stirring with an outboard motor will often start decomposition. Copper sulphate snow is most frequently used to control winter forms of algae, but in high concentrations it will kill fish. To kill algae growing on the pond bottom, make a water solution containing 8 pounds of copper sulphate snow for each acre-foot of water to be treated. Mix the solution thoroughly and apply with a sprayer or mix it into the water with an outboard motor. Floating mats of winter algae may be treated by broadcasting copper sulphate snow over the masses at the rate of 3 pounds per 1,000 square feet of surface treated. No more than one-fourth the surface area of a pond should be treated at one time, otherwise a lethal concentration of copper for fish may be reached, or the oxygen may be dangerously lowered by the decaying algae. Copper sulphate treatments may be repeated several times at weekly intervals without danger to the fish. The summer-growing branched algae (Pithophora) cannot be controlled until after the pond is drained. Before refilling the pond, the damp masses of algae should be sprinkled with copper sulfate snow at the rate of 3 pounds per each 1,000 square feet. This will usually prevent regrowth of this pest the following year if the pond is adequately fertilized. [69] AVERAGE WEIGHT PER THOUSAND OF MINNOWS OF VARIOUS SIZE GROUPS Total length Inches GOLDFISH: Weight per 1,000 Pounds 1 2 21 2.9 5.4 9.0 3 31/2 17.0 24.5 4 BROOD GOLDFISH: 40.0 7 8 9 10 11 FATHEADS : 210 320 475 630 750 11/ 2 2%1/2 1.9 8.6 8.6 8 31/ GOLDEN SHINERS: 15.0 21.5 2 2% 3 31/ 4 41i 5 51/ 3.9 5.4 8.6 13.5 19.0 31.5 44.0 60.0 [70] LITERATURE CITED (1) INDIAN COUNCIL OF AGRICULTURAL RESEARCH. Madras Rural Pisicul- tural Scheme. 1951. (2) (3) (4) (5) Progress Report April 1950 to March 1951: 72 pp. LAWRENCE, J. M. Construction of Farm Fish Ponds. Ala. Agr. Expt. Sta. Circular 95, 55 pp. illus. 1949. LIN, S. Y. Notes on Fish Fry Industry of China. eries Council Proceedings: 65-71. 1949. Indo-Pacific Fish- SWINGLE, H. S. Experiments on Pond Fertilization. Ala. Agr. Expt. Sta. Bull. 264, 34 pp. 1947. . Experiments with Combinations of Largemouth Black Bass, Bluegill, and Minnows in Ponds. Trans. Amer. Fish Soc. 76 (1946), pp. 46-62. 1949. SWINGLE, H. S. AND SMITH, E. V. Fertilizers for Increasing the Natural Food For Fish In Ponds. Trans. Amer. Fish Soc. 68 (1938), pp. 126-135. 1939. TIDD, W. M. Studies on the Life History of A Parasitic Copepod, Lernaea cavassii Tidd, Ph.D. Thesis, Ohio State University. 1937. VAAS, K. F. Preliminary Report on Air Transport of Live Fish in Sealed Tins Under Oxygen Pressure. General Agr. Res. Sta., Bogor, Indonesia. (Unpublished). 1951. (6) (7) (8) [71]