Catfish Farming in Florida

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Title:
Catfish Farming in Florida
Physical Description:
Fact Sheet
Creator:
Walsh, S.J.
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.
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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
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Published
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"Date first printed: March 1991; date reviewed: February 1999."
General Note:
"Circular 710"

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University of Florida Institutional Repository
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University of Florida
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All rights reserved by the submitter.
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IR00003778:00001


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1.This document is Circular 710, one of a series of the Department of Fisheries and Aquatic Sciences, Florida C ooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Date first printed: March 1991; date reviewed: February 1999. Please visit th e FAIRS Web site at http://hammock.ifas.ufl.edu .The Institute of Food and A g ricultural Sciences is an equal opportunit y /affirmative action emplo y er authorized to provide research, educational information and other services onl y to individuals and institutions that function without re g ard to race, color, sex, a g e, handicap, or national ori g in. For information on obtainin g other extension publications, contact y our count y Cooperative Extension Service office. Florida Cooperative Extension Service / Institute of Food and A g ricultural Sciences / Universit y of Florida / Christine Ta y lor Waddill, Dean2.S. J. Walsh, Graduate student, Department of Zoology and the Florida State Museum; W. J. Lindberg, Assistant Professor, Aquac ulture Extension Specialist, Department of Fisheries and Aquatic Sciences, Cooperative Extension Service, Institute of Food and Agricultural Sciences, Unive rsity of Florida, Gainesville, 32611. The use of trade names in this publication is solely for the purpose of providing specific information. It is not a guarantee o r warranty of the products named, and does not signify that they are approved to the exclusion of others of suitable composition.Catfish Farming in Florida1 S. J. Walsh, W. J. Lindber g 2Commercial catfish farming is an important agriculturalBefore building facilities and attempting to raise catfish, industry in the United States, alt hough Florida has laggedone must become thoroughly fam iliar with marketing behind other southeastern states. More than 100,000 acres ofpotential, investment costs, and environmental constraints water are currently used to produce around 225 m illionthat apply to a given area. Prices of farm-raised catfish for pounds of catfish yearly in the United States. Of this market,consumption are currently noncompe titive with wild-ca ught about 275,000 p ounds of food-sized fish were raised on 88fish in Florida. Moreover, consumers in the state seem to acres in Florida during 1981. The low commercialhave a preference for shorts" or "sharpies," i.e., fish of a production of catfish in Florida, compared with otherrelatively small-sized dressed carcass (2-5 ounces). Farmers southeastern states, is primarily the result of marketing andwho may be considering production of food fish should environmental constraints. A lack of adequate processinginvestigate marketing outlets for their product well before facilities for farm-raised fish and soils that are not suited forconstructing fac ilities and stocking fish. Likewise, anyone large, conventional embankment ponds have impededintending to pr oduce fingerlings for sale as seed stock should development of the catfish aquaculture industry in the state.be sure that they w ill be able to sell and transport their fish Nonetheless, catfish farmers are increasing their endeavorssu ccessfully. Producers must make a preliminary assessment in Florida and prospects for future development of theof expected economic expenditures and returns to determine industry may be promising.the potential profitab ility of catfish farming. The greatest This publication addresses the basic techniques andand supplies. Major operating costs are feed, fingerlings (for procedures used in culturing catfish and is intended to be arearing as food fish), labor, fuel, electricity, chemicals, and general guide for the farmer who is contemplating raisingprocessing or transportation costs. A marketing analyst catfish in Florida on a commercial basis. Catfish farmersshould be consulted for assistance in estimating ec onomic often specialize either in producing food-sized fish forinvestments and profits. Environmental constraints such as processing and marketing to wholesale and retail outlets, orthe feasibility of p ond construction, and water qua lity and in spawning and rearing fry and fingerlings for stocking toquantity must be carefully considered when planning a fish grow-out ponds and other aquatic systems (e.g., racewaysfarm and making an economic analysis. and cages). capital outlays will be land, p ond construction, equipment, Several unique features of Florida's topography, climate, and aquatic systems show promising avenues for

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Catfish Farmin g in Florida Pa g e 2Februar y 1999 Figure 1 Male ( left ) female ( ri g ht ) .development of the catfish farming industry. Construction ofCatfish farmers generally prefer brooders in the 2-10 appropriate ponds for culturing catfish may be severelypound range; smaller females do not produce as many eggs limited by soil types and topography throughout much of theas larger ones, and bigger fish may be difficult to handle. state except in parts of the panhandle. However, there mayChannel catfish reach optimal breeding condition in three to be good potential for rearing fish by nontrad itional methodsfour years, when 40-50% of the fish may be expected to such as in raceways or in cages placed in canals, borrow pits,spawn under good cond itions. Scientists are currently or other suitable bodies of water. Because of the warmattempting to breed strains that will mature earlier. Proper climate and long growing season, Florida farmers couldnutr ition of mature fish throughout the year is essential to possibly supply fingerlings or fresh food fish to markets inensure su ccessful spawning, because the number and size of other states out-of-season or on a year-round basis.eggs produced by a female is strongly influenced by diet. Cultivation of yellow bullheads ( Ictalurus natalis ), brown bullheads ( I. nebulosus ), white catfish ( I. catus ), or otherIt is important to select the proper ratio of male and species could provide alternatives to rearing channel catfishfemale brooders. A ratio of two or three females for each ( I. punctatus ). Some of these species might be suitable formale is ideal. One male can mate with two or more females supplementing current consumer markets, and they may bein a single spawning season if the eggs are moved to a more amenable to culture under certain cond itions than arehatchery or incubation chamber. Although catfish normally channel catfish. However, culture techniques are best knownpr oduce offspring in a 1:1 sex ratio, do not take this for for channel catfish, and the methods and procedures ou tlinedgranted when buying br ooders. Males grow faster than here are those that apply principally to channel catfish unlessfemales, so when fish reach 2-3 pounds, up to 80% of the otherwise noted.largest individuals in the population may be males. It is ensure a proper ratio of males and females.FINGERLING PRODUCTIONBrood Stock Manag ement Selection of Brood StockSuccessful fingerling producers select high quality brood fish and maintain them in good health to obtain maximum yields of offspring. Many catfish producers prefer to buy mature fish rather than waiting for fingerlings to reach spawning age. The best source of brood fish is a reputable hatchery. However, be careful not to buy culls, or fish that have been discarded because they have undesirable traits. Fish-farming trade magazines usually carry advertisements for brood stock available thr ough established producers and growers. It is advisable to inspect brood fish closely before buying to ensure that healthy fish are obtained. Avoid purchasing fish recently taken from the wild, since they are often unreliable spawners and their fingerlings may grow more slowly and be less resistant to diseases than fingerlings from established hatchery stocks. Be especially careful to avoid any sources having a history of channel catfish virus disease, since this pathogen is untreatable and can spread quickly and destroy an entire stock. Inbred strains are less desirable than genetically superior crossbred strains. Healthy brooders should be full-bodied and free of sores or hemorrhages on the skin. Thin or emaciated fish may be old, diseased, or underfed. advisable to determine the sex of each brooder you buy toDeterm ining SexBoth primary and secondary sex characteristics are useful in distinguishing males and females. Primary sex characteristics are those features specifically involved in reproduction, whereas secondary sex characteristics are not directly involved in spawning. The primary characteristic used to distinguish the sexes is the urogenital opening; the secondary characteristics relate to coloration and body shape. (Figure 1) Secondary characteristics are most prominent during the spawning season. Males are usually larger and have broader heads than females of the same age. As the spawning season

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Catfish Farmin g in Florida Pa g e 3Februar y 1999 Figure 2 Male ( ri g ht ) female ( left ) .approaches, males become lean, develop large muscularan assistant carefully and gently slide a blunt probe, such as heads that are wider than their bodies, and sometimesa thin wire, over the genital area toward the tail, with the become darker, especially on the lower jaw. Females' headspoint leading the probe. Be cautious not to break the skin or are narrower than their bodies when viewed from above.penetrate the flesh with the probe. If the point of the probe They also develop soft, greatly distended bellies as thecatches in the genital opening, the fish is most likely a spawning season approaches.female. Drawing the probe across the genital area in the Preliminary identification of sex should be confirmed bycause the probe to catch on the genital pap illa if the fish is a examining the urogenital opening. This is particularlymale. important with young fish and during the fall or winter when secondary sex traits are less pr onounced. With practice, one can reliably use the following method to determine the sex of fish as small as one pound. (Figure 2) The fish should be turned upside down for examination of the genital area, which can be seen as a fleshy area about midway between the pelvic and anal fins. Two openings should be visible when examined closely: the one nearest the head is the anus, and the one nearest the tail is the genital pore. In males the genital pore terminates on a fleshy, nipple-like structure (the genital papilla), which usually becomes swollen and somewhat rigid as spawning season nears. The genital area of females is oval and flat, with the anus separated from two other openings by a small flap of skin. The slit or gr oove toward the tail end contains a urinary pore and the genital pore. Immediately prior to and during the spawning season, the entire genital area of the female becomes red, swollen, and may be covered with a thin layer of mucus. A probe is useful in determining the sex, especially in young or nonbreeding fish. Immob ilize the fish by holding it belly upward with one hand grasping the head and the other hand firmly holding the tail region. With the fish's head below your chest and the tail held away from your body, arch the fish's belly upward. This will allow the male genital papilla or the female s lit to become more visible. Then have opposite direction, from the tail side toward the head, shouldNutritionGood spawning success requires a proper diet for brooders, especially in the fall and early spring months. During warm weather feed a nutritionally complete diet of about 35-40% protein at a concentration of 1-2% of the stock body weight daily (Table 1). Catfish do not require feeding when water temperature falls below 50 F (10 C). When water temperature is between 50 and 65 F (10-18 C), feed approximately 0.50-0.75% of the fishes' body weight three times per week. Estimate the amount to feed by observing feeding vigor, if possible. This can best be accomplished by using a floating pellet. During warm weather, the proper amount of food to offer is that which will be eaten in about 10 minutes. Feeding activity declines when the spawning season begins and during cold weather.StockingTotal weight of brood fish should not ex ceed 1200 pounds per acre at any time, hence p onds should be stocked initially at about 800 p ounds of fish per surface acre to allow for weight gain. Successful spawners should gain about 50% of their weight from one spawning season to the next. Old, sick, and undesirable brood fish should be removed each spring and replaced with young brooders to maintain the total initial stocking density and to enhance vigor and productivity by reducing inbreeding. The most popular brood ponds in more northern states are between 1 and 10 acres; smaller ponds may undergo extreme temperature changes and reduce spawning success, while larger ponds are difficult to manage. Problems with pond construction, temperature control, and weed management in Florida waters dictate that the most convenient size for br ood ponds should be 1/10 1 acre. Brood fish should be stocked in more than one pond to minimize the likelihood of wholesale destruction of an entire stock from disease, oxygen depletion, or other catastrophes.

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Catfish Farmin g in Florida Pa g e 4Februar y 1999rearing techniques are used.Spawning ManagementChannel catfish begin spawning in late spring when water temperature reaches about 75 F (24 C). Males prepare nests in hollow logs or similar shelters and aggressively attack intruders. A female that is attracted to a nest will mate with the male over a period of several hours, depositing a large, yellow, jellylike egg mass. The number of eggs laid is dependent on the size of the female and averages around 2, 000-3,000 per p ound of body weight. A one p ound egg mass will contain about 10, 000-11,000 eggs. After spawning, the male chases the female away and guards the eggs. A single male may spawn with more than one female in one season.Use Of Spawning SheltersArtificial spawning containers should be provided to enhance spawning success and facilitate removal of eggs and young. Commonly used items include milk cans, nail kegs, ceramic or earthenware crocks, wooden boxes, ammun ition cans, and plastic or metal buckets and drums. The spawning receptacle must be of sufficient size to accommodate the brooding pair and s hould have an opening just large enough for them to pass through. A hinged lid w ill make it easier to check for spawning and to remove eggs. Spawning containers should be provided for 50-90% of the males, by placing containers in water 12-30 inches deep, 1-10 yards apart, and with the opening toward the pond center. Each nest container can be marked with a float or flag to indicate its position. Containers should be placed in ponds at a time appropriate for the target date of fingerling production. Most spawning occurs at water temperatures between 75 ( and 85 F (24-30 C), with an optimum around 80 F (27 C). Because of the large latitudinal temperature gradient in Florida, channel catfish can be expected to spawn at quite different times between about March and July throughout the state. As a result, more southern farms may have the greatest potential for supplying early seed stock to markets in the north. Spawning activity sometimes diminishes for no apparent reason. Additional spawning may often be stimulated by lowering the water level of the pond about one foot and then rapidly refilling the p ond, or by occasionally moving unoccupied containers. Since not all females spawn and a proportion of the eggs, fry, and fingerlings do not survive, about 1,000 fingerlings w ill be pr oduced per pound of healthy female brooder if proper brood stock, hatchery, andSpawning MethodsA variety of methods are commonly used to spawn catfish. Some producers attempt to induce spawning by injecting brooders with hormones. Such injections may be useful in stimulating fish to breed out-of-season or in unnatural enclosures such as pens and aquaria. Catfish will respond to intraperitoneal injections of pituitary extract from carp and other fish, as well as synthetic hormones. Carp pituitary is typically given in doses of about 6 mg per pound (450 g) of fish in three injections over 24 to 48 hours. Prespawning catfish also respond well to a single injection of human chorionic gonadotropin (HCG) at an optimum dose of about 800 International Units (I.U.) per p ound (450 g). Both ripe males and females may be injected. The following methods are the most popular techniques used in spawning catfish: 1.Spawning and Rearing Pond Method This method requires the least sk ill, labor, and facilities. Spawning containers are placed in the pond, and the fish are allowed to spawn and hatch the eggs. Fry are left in the pond and cultured until ready for harvest. This met hod is unreliable, causes ponds to contain different size and age groups, and is not recommended for commercial production of catfish. In some cases it is a suitable method of producing catfish for recreational angling or noncommercial harvest. 2.Egg Transfer Method, Open Pond Spawning This method is a productive way to spawn catfish but requires great technical and financial expenditure. Brooders are allowed to spawn in containers within the pond, but the fertilized eggs are removed and incubated in a hatchery. Removal of eggs minimizes the spread of diseases and parasites from the adults to the young, reduces predation on fry by the adults, and provides easier means to control stocking densities. Spawning containers should be examined every two to four days, preferably in the late morning or afternoon, since most spawning probably occurs during the night or early morning. Eggs should be carefully removed as soon as they are found. Since male catfish aggressively defend their nests and can inflict painful bites, it is advisable to wear gloves and exercise caution when removing eggs or fry. Disturbed males may also eat or dislodge their eggs, so it is sometimes best to first chase the male away from the spawning container. The adhesive egg mass should be gently scraped free of the floor of the container using a plastic spatula or similar

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Catfish Farmin g in Florida Pa g e 5Februar y 1999 Figure 3 Removal of e gg mass from spawnin g container. Figure 4 Spawnin g pens.device, and then carefully lifted into a bucket containinguse in Florida, but there may be good potential for this pond water. Eggs may be left in a bucket in the shade for 10met hod in pit p onds, canals, sinkhole and solution lakes, to 20 minutes, but if they are near hatching or if transport toreclaimed phosphate pits, and other aquatic systems unusual the hatchery will be l onger, aeration should be provided.or unique to the state. Never place eggs in direct sunlight or transport them in coolers and other tightly covered containers that might resultPens are usually built in at least 3 feet of water al ong a in suffocation. (Figure 3)bank to minimize the amount of materials needed and for 3.Fry Transfer Method, Open Pond Spawning This method is similar to the egg transfer method,materials s hould be used to construct recta ngular pens about except that the male brooder is allowed to incubate the eggs4 x 6 feet and extending 12-24 inches above the water until hatching. Newly-hatched fry are transferred from the spawning containers to the hatchery or nursery ponds. Spawning containers should be checked every three days, and when an egg mass is found a small clump of eggs s hould be gently pinched off and examined closely to determine the approximate age of the clutch (Table 2). Remove the fry one day after the predicted hatching date. Newly-hatched fry have a large yolk sac that impedes their movement, but they are still capable of swimming. Fry can be carefully caught with a small fine-mesh net or gently poured into a bucket of pondA pair of ripe brood fish of similar size should be water and transferred to the nursery. After counting the fryintroduced into each pen. It is important to select fish, (see "Counting Fry"), they should be released into theespecially females, that are nearly ready to spawn. Some nursery by slowly submerging the bucket. If the waterproducers who use this method prefer to inject brood fish temperature of the nursery differs from that of the broodwith spawning hormones a day or two before placing them pond, be sure to properly acclimate the fry as during haulingin the pens. Cages s hould then be checked daily and any and stocking.female that is being harassed or injured by a male should be 4.Pen Spawning Pen spawning uses submerged enclosures made ofbe moved to the nursery or the male may be allowed to wood, concrete, wire mesh, or a combination of materials.incubate them to hatching. If spawning does not occur in one Although this method requires add itional construction andto two weeks, double check the sexes of the pair and labor costs, it has the advantage of allowing selectiveexchange brood fish if n ecessary. mating. Pen spawning techniques are not currently in wide ease of observing and handling fish. Galvanized chain link fence, plastic-coated wire mesh, or other nonrusting surface, with the narrow side open against the shoreline. Adjacent pens can have common sides to further reduce construction costs. Sides of the pen must be embedded in the bottom to prevent brood fish from escaping. Mesh size must be large enough to allow for good water circulation, but not so large as to permit the escape of brood fish; meshes of -2 inches are usually satisfactory. A spawning container is placed in the pen, usually with the receptacle opening toward the center of the pond. (Figure 4) removed at once. It is very important to transfer the female soon after spawning to prevent her from being seriously injured or killed by the male. Following spawning, eggs may

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Catfish Farmin g in Florida Pa g e 6Februar y 19995.Tank Method Tank or aquarium spawning is the most intensivePaddles should be spaced at appropriate widths to method of spawning management because it requiresaccommodate six to eight wire-mesh baskets in which eggs considerable investments of time, labor, and facilities.are suspended. Baskets made of 1/4 inch plastic-coated Aquaria, tanks, or troughs of at least 50 gallons ( 200 liters)hardware cloth and about 3 inches deep are hung by wires are used as spawning enclosures. A pair of ripe brooders isfrom the sides of the tr ough so the waterline is just below the selected and spawning is induced by injecting the female orbasket tops. Paddles should be long enough to reach well both fish with pituitary extract or HCG. Depending on thebelow the baskets to gently roll the egg masses and force dose of hormone, spawning usually ensues within a day oroxygen-rich water through them. Water should be applied to two of injection, but some females may require additionalone end of the trough at a rate that w ill allow one complete injections. As soon as spawning is completed, the eggs arewater exchange in about 45 to 60 minutes (about 2 to 3 transferred to the hatchery and the aquarium can be stockedgallons per minute in a 100-gallon trough). A standpipe may with a new brood pair, or the same male can be used with abe fitted into a drain at the other end of the trough to control fresh female following a resting period.water depth. The standpipe must be screened to prevent fry The tank method has several advantages over otheravoid clogging and trough overflows. Provisions should be techniques: (1) variables such as temperature, light, andmade for emergency generators to supply power in case of water chemistry can often be controlled more easily; (2)electricity outages. spawning period can sometimes be altered, allowing for earlier seasonal production of fry or lim iting spawning to times that are convenient for the culturist; (3) fish that might not otherwise spawn may often be induced to; (4) diseases and parasites can be more easily controlled; (5) selected matings can be performed and easily recorded. Major disadvantages of the tank method are that (1) there are greater risks of losses from power outages, plugged pipes, and other mechanical failures; (2) the number of eggs produced per man-hour may be lower than other methods; (3) the tank method is comparatively expensive.The HatcheryThe most efficient hatcheries use incubation chamberstolerated, but lower temperatures increase the hatching time for hatching eggs, since predation, cannibalism, and diseaseand might increase disease problems. can be reduced and stocking rates can be easily monitored. Hatcheries range from simple wooden paddle-wheel troughsOxygen levels in troughs must be maintained at a to more sophisticated devices available through commercialminimum of 6 parts per m illion (ppm) to supply adequate equipment suppliers. Hatcheries need not be elaborate, soamounts to eggs and fry. Total hardness and total alkalinity long as good water qua lity and disease control measures ares hould ex ceed 20 ppm, and the pH s hould be between 6.5 maintained.and 8.5 for best results. Acidic or soft water can be correctedTrough constructionA typical incubation chamber consists of a flatbottomed wooden, fibergla ss, aluminum, or stainless steel (14-gauge) trough about 8 to 10 feet l ong, 18 to 24 inches wide, and 10 to 12 inches deep (about 100 gallons). Some hatcheries have a divider in the middle of the trough for reinforcement and to allow eggs of different ages to be incubated at the same time. To provide adequate aeration, troughs are equipped with a series of paddles made of galvanized tin or similar material. Paddles should be mounted above the center of the tr ough on a one-inch pipe shaft, driven by an electric motor at 30 rpm. from escaping, and should be inspected and cleaned often toWater QualityProper water conditions are essential for successful fingerling production. A clean water source such as a well is best for hatching eggs, since risk of disease is minimized if there are no fish or fouling organisms in the water supply. However, water from many wells and other sources must often be aerated and warmed prior to filling hatchery troughs. (Figure 5) Water temperature should be between 75 and 82 F (24 and 28 C). Hatching occurs in about 6 days at an optimal temperature of about 80 F for artificial incubation. Temperatures from 68 to 86 F (20 to 30 C) can be by adding limestone or a buffer on a case-by-case basis. Further information on water quality is contained in Florida Extension Circular 715, "Management of Water Quality for Fish."

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Catfish Farmin g in Florida Pa g e 7Februar y 1999 Figure 5 Hatcher y trou g h with paddles.Disease ControlEggs and fry are highly susceptible to bacterial and fungal infections. Proper treatment requires complete familiarity with identification of pat hogens and use of chemicals; additional references and diagnostic laboratories should be consulted for greater details of material presented here. The best disease control is prevention by maintaining adequate aeration, clean water, and temperatures below 82 F (28 C). Equipment should be cleaned frequently and disinfected to prevent contamination. Eggs should be checked daily and any debris, shells, and dead or badly infected eggs removed with a siphon. Bacterial and fungal infections often appear as cloudy or cottonlike patches on eggs and should be treated or isolated when first detected. Chemical treatment may be successful provided standard recommended doses are not exceeded. Conversion tables and proper dosages are available in Plumb et al. (Southern Coop. Ser. No.225) and Jensen et al. (Alabama Coop. Ext. Service Circ. ANR-327). Bacterial outbreaks can be treated by dips or baths in terramycin (20 ppm), potassium permanganate (3 ppm), and other drugs. Eggs with fungal infections can be treated with formalin (100 ppm for 15 minutes) and may require simultaneous treatment for bacterial growth. Formalin should never be used with eggs that are near hatching. Sanitary conditions maintained in the hatchery may provide added protection from parasites, channel catfish virus disease (CCVD), and other infections following hatching.Fry ManagementHandling FryWithin one to two days of hatching young sac fry should be acclimated and transferred from the hatching troughs to rearing tanks, troughs, vats, screened boxes, or other facilities using a 1/2 inch or larger siphon or small net. After hatching, sac fry swim through the egg baskets and school together in tight clusters near the bottom. Fry rely on their large yolks and do not begin to feed until they become darkly pigmented and absorb their yolk sacs (about three to four days after hatching). Rearing tanks must have clean, well-aerated running water and should be scrubbed and sterilized with a mild chlorine (1 teaspoon of household bleach per gallon of water for five minutes) or formalin (1 part: 4000 parts water) solution between each crop of fry. Be sure to thoroughly wash chlorine or other antiseptics off equipment with three or more rinses in fresh water. Keep young fry away from bight lights to reduce stress.Counting FryThe number of fry transferred from hatching troughs to temporary rearing chambers can be estimated using volumetric or gravimetric methods. It is best to combine clutches of fry that are about the same age in order to facilitate counting and to keep equally-sized individuals together. Estimate the number of fry by water displacement in a household measuring cup or graduated cylinder prior to introducing them into rearing tanks. A r ough estimate is that about 1,000 one-day-old fry w ill displace one ounce of water. A more accurate approximation can be obtained by counting a small sample of 200-300 fry, measuring the amount of water that they displace, and then recording the water level change for all fry. The total number of fry can then be estimated by Equation 1: EXAMPLE: (1)A sample of 300 fry displaces water level in a 100 ml graduated cylinder from 50 to 62 ml. (2)The entire clutch of fry displaces the water level in a larger container from 500 to 900 ml. (3)The total number of fry can then be calculated in Equation 2:

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Catfish Farmin g in Florida Pa g e 8Februar y 1999 Figure 6 Countin g fr y b y water displacement in a g raduated c y linder.Estimating fry number by weight is similar to the aboveother nutrients may be required to fortify the diet. Young fry method. Water in a container is weighed, a sample of fry iss hould be fed often with enough meal that w ill be eaten in 15 counted and then added to the water, and the increase into 20 minutes. Avoid overfeeding and distribute meal over weight is recorded. The total weight of all fry is thenthe water surface using a screen or fine strainer. Since fry measured and the total number of fry can be approximatedgrow rapidly the pellet size and amount of food must be using the same general formula as that for volumetricgradually increased (Table 3). counting. Estimating the number of fry by these methods allows the producer to determine appropriate stocking densities and feed allotments when moving fry to facilities for growing fingerlings. In addition, the number of fingerlings graded into various size classes must be counted when sold or transported to markets (see "Grading Fingerlings"). (Figure 6)Feeding FryFry begin swimming up to the surface of the water and around the edges of the tank when they are ready to feed. Small ground pellets, "crumbles," and granules ("fry starter") are typically used for feeding fry. A nutritionally-complete, high protein diet is recommended for maximum growth (ideal feed contains at least 45-50% crude protein, of which 60% of the protein should be fish meal). In itial food particles should be 0.35-0.60 mm (standard seive gauge 30-40). Small particle feeds have greater surface areas and may lose valuable nutrients by leaching and erosion during processing or storage. Supplemental vitamins, minerals, orRaising Fingerlings Pond Preparation and Pest ControlCatfish can be grown to fingerling sizes, suitable for marketing as seed stock, in a variety of rearing facilities that include ponds, troughs, and raceways. In general, many of the precautions and techniques of raising food-sized fish in production ponds also apply to the methods used in rearing fingerlings. To be successful, a producer must maintain optimal water quality by practicing routine procedures such as the following: (1) take care to exclude all wild fish, predatory aquatic insects, tadpoles, and other potentially noxious animals from rearing areas; (2) monitor water chemistry frequently and take appropriate remedial measures to control improper levels of dissolved oxygen, pollutants, pH, sediments, etc.; (3) prevent excessive growth of aquatic weeds and avoid overfeeding and other sources of organic waste; (4) record water temperature often and be especially cautious to avoid heat-related stress; and (5) use appropriate drugs and chemicals, following local regulations and suggested procedures, to contain or eliminate diseases and parasites only after conventional preventive measures have failed. Diseases are a constant threat to cultivated catfish and are of special concern to fingerling producers. Prevention of serious diseases requires good management by minimizing stressful conditions such as unfavorable environmental factors, improper handling, and poor nutrition. Channel catfish virus disease (CCVD) poses a particular threat to fingerlings and requires special consideration. Channel catfish virus infects fingerlings less than 6 inches long and is highly contagious and usually fatal. Symptoms include hemorrhaging at the base of the fins and in the skin, distended abdomen filled with a clear, yellowish fluid, exophthalmia (pop-eye), pale gills, and erratic swimming behavior (these symptoms should not be considered as exclusive evidence for the disease). CCVD occurs primarily during hot weather when water temperatures exceed 68 F (20 C), and develops more rapidly and results in greater losses as temperature increases. Very few effective

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Catfish Farmin g in Florida Pa g e 9Februar y 1999treatments are available for viral diseases of fish, hencetemporarily holding them in screened boxes within ponds CCVD must be prevented to avoid losses of entire stocks. Auntil they reach slightly larger sizes. diagnostic laboratory or fisheries specialist should be consulted to verify suspected cases of the disease. TheTo determine optimal stocking rate, divide the following measures are imperative to prevent outbreaks ofanticipated total weight produced per acre by the weight of CCVD:the average sized fingerling desired for harvest. Since a day should generally not be ex ceeded, a maximum of about 1)Prevent stress from low oxygen. 2)Do not move fingerlings when water temperature is over 85 F (29 C). If fingerlings must be moved during the summer, they should be handled gently and as briefly as possible (however, do not move fish if CCVD is suspected). 3)Prevent poor water quality from developing in rearing facilities by avoiding excessive buildups of ammonia, organic debris, and other toxic substances. 4)Avoid large outbreaks of external parasites on fingerlings by using prophylactic measures. Do not treat for external parasites if CCVD is already present. 5)Avoid very high stocking densities (i.e., greater than 150,000 fry per acre). 6)Do not use nets or other equipment that have been used in ponds or tanks where there has been a recent CCVD outbreak, without first disinfecting in Roccal (1 ,000 ppm for 5 minutes) or HTH (calcium hypochlorite) at 40 ppm for 5 minutes.Stocking FryThe optimal number of fry to stock depends on the management intensity, type of rearing facility, feeding schedules, water temperature, and other factors. Initial stocking density generally depends on the final size of fingerlings desired at harvest. Growth rate is determined by interactions between quantity of f ood consumed, stocking density, and water temperature, hence size of fingerlings at harvest may be highly variable (Table 4). At very high stocking densities, it is unwise to offer maximum amounts of food because water qua lity can deteriorate rapidly. Fry should be stocked into rearing areas during the cool evening or morning hours by slowly c onditioning them to the water, using aerated buckets or other containers to transport them. Fry stocked in ponds may survive better and can be more easily fed if they are provided with shelters such as wooden or plastic boxes ar ound which they congregate. Some producers prefer to give added protection to fry by maximum feeding rate of 100 pounds of feed per acre per 3,500 p ounds of fish per acre can be attained at harvest time. The following examples illustrate sample calculations required to estimate common stocking rates: Example 1. If 0.06 pound average fish (6 inches) are desired for harvest, then the required stocking per acre is (see Equation 3): Example 2 .If 0.02 pound average fish (4 inches) are desired for harvest, then (see Equation 4):Feeding FingerlingsSmall fingerlings have large appetites and s hould be fed nutritionally-balanced diets at least two to six times daily for the first two weeks. As fingerlings grow, they can be fed larger pellets (Table 3), but they begin to eat less food in relation to their size. "Crumbles" or crushed pellets can be replaced with 3/16 inch pellets of at least 36% protein when fingerlings are four to six weeks old. Extruded or floating pellets are preferred by most catfish producers because the fish can be seen as they eat. Savings in food costs of 10-15% can sometimes be realized by using a combination of about 85% sinking and 15% floating pellets. However, feed loss must be avoided by distributing pellets near areas where fingerlings congregate and by placing sinking pellets over areas of hard bottom and free of rooted vegetation. Shelters and containers can be used to attract fingerlings to desired feeding areas. The amount to feed is determined by fingerling size, stocking density, and water temperature. Most suggested feed schedules are rough guides and the manager must use

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Catfish Farmin g in Florida Pa g e 10Februar y 1999 Figure 7 Box-t y pe g rader for catfish fin g erlin g s. Figure 8 Tank with aerator for haulin g fin g erlin g s.good judgement in estimating a proper allowance. Standard recommended feeding rates are presented in Table 5. Actual feed allowances, usually expressed as pounds/acre/day, will vary widely but generally should not ex ceed 35 pounds/acre/day during summer to prevent oxygen shortages. In cold weather, fingerlings should be fed 1.5% of their estimated weight three to six days per week. Fingerlings fed from November to March in Florida will probably gain at least 25-40% of their initial body weight. Fish weight should be estimated weekly, and perhaps daily, in order to make accurate adjustments of feeding percentages. At very high stocking densities and high water temperatures it is unwise to offer maximum amounts of food because water qua lity can deteriorate rapidly.HarvestingWhen fingerlings are 3-10 inches long they can be harvested for marketing as seed stock. Harvesting can be done year-r ound but is discouraged when water temperature is over 85 F (29 C). Harvest during cool morning hours and handle fingerlings as briefly as possible during warm months to lessen stress. Fingerlings grown in ponds can be removed by seining with a 100-200 foot net. About half of the seine s hould be stretched and staked in the water, parallel to the shore and about 50 feet from the bank near a hard-bottomed feeding area free of debris. Excess netting at the ends of the seine can be rolled or folded and hauling ropes extended from the seine to stakes on the shoreline. Fingerlings should then be fed in the trapping area for a few days to accustom them to the net. Harvesting is done by pu lling the net toward the shore and around the fingerlings when they are actively feeding. Fish should then be dipped from the seine and loaded directly into grading vats or hauling equipment. (Figure 7) The sharp pectoral and dorsal spines of fingerlings can become tangled in nets and cause undue stre ss. Entanglement can be reduced by dipping nylon seines and nets in an asphalt-base net coat prior to harvesting, or by using polyethylene nets. Partial grading of different-sized fingerlings can be done in the pond by using seines with different mesh sizes (Table 6). Some producers use traps to successfully harvest fingerlings from ponds. Harvesting fish from raceways, troughs, cages, and other fac ilities can be c onveniently accomplished using catchment basins, dip nets, and other equipment.GradingFingerlings must be graded and counted into different sizes before shipment. (Figure 8) Grading is most easily done in holding tanks or vats by using specially constructed boxes. Box-type graders usually have aluminum or stainless steel rods that are spaced at appropriate widths and retain certain size fish but allow smaller ones to pass through. Recommended bar widths for grading fingerlings are given in Table 6.CountingFingerlings may be sold by weight, length, or a combination of both. Counting them is more accurate if they are first graded into uniform size classes. At least three samples with a minimum of 200 fish each are c ounted and weighed before, midway, and at the end of loading. The weight per thousand fingerlings is estimated from the samples. All of the fingerlings are then weighed as they are loaded into the transport tank, and the total number of fish is estimated from the average weight of the individual samples. For example, three samples of 200 fish each might weigh 10,

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Catfish Farmin g in Florida Pa g e 11Februar y 199911, and 12 ounces, or a total of 33 ounces (2.06 pounds) for(0.4-0.8 pounds/ 100 gallons of water) to transport tanks to 600 fish. If a total of 500 p ounds of fish is loaded into thereduce stre ss. S uggested loading dens ities are presented in tank, then the number can be estimated as in Equation 5:Table 7. If fingerlings are transported in conventional The average weight in pounds of each 1, 000 fish can then be calculated as in Equation 6:Transporting FingerlingsHealthy fingerlings can be transported alive for relatively long distances with proper equipment and careful handling. Hauling tanks vary in design but should always be well insulated and equipped with aerators or agitators and filled with clean, fresh water. When using tanks deeper than 30 inches or hauling crowded fish loads it is necessary to use efficient aerators and to have bottled oxygen for emergency backup. Oxygen should be released thr ough porous diffusers as small bubbles into the water. The number of fingerlings that can be safely hauled depends on the tank volume, efficiency of the aeration equipment, length of haul, water temperature, and size and condition of the fish. Fingerlings should not be fed for 12 hours prior to l ong hauls to prevent excessive buildups of toxic wastes. Oxygen should be maintained at levels greater than 4-5 ppm and the temperature should be kept cool if possible (about 60 to 65 F). Some producers add salt hauling equipment, be sure to keep them out of the agitator or aerator by screening all intakes with 1/16 inch mesh. Catfish fry and small fingerlings can be shipped in 3-mil polyethylene bags for short distances. Bags should have four corners to prevent fish from congregating and suffocating in collapsed corners. Bags are doubled and partially f illed with water before placing fry in them, then filled with oxygen (in a volume ratio of 3 units oxygen: 1 unit water) and securely tied with rubber bands or string.RAISING FOOD FISHRearing Facilities Pond ConstructionPond culture is the most common type and often the most productive way to raise catfish for marketing as food. The number, size, depth, and shape of ponds suitable for a given area are often limited by the local topography, soil type, and available water supplies. In areas with moderate topographical relief and nonporous soils, embankment or hill ponds are often constructed by building dams or earthen dikes across streams or runoff basins. Areas with flat terrain or porous soils are generally more suitable for leveed or excavated ponds, constructed by cutting basins into the water table. In most states where catfish are commercially produced, good cond itions generally exist for embankment and/or excavated ponds ranging in size from about 1 to 20 acres or more. In Florida, however, prevailing geological conditions are generally not as suitable for conventional pond types used for rearing catfish. There are three relatively distinct geographical regions in Florida insofar as pond construction and management is concerned. These regions are west Florida (the panhandle east to about Monticello), north Florida (north of Ocala), and central and south Florida (south of Ocala). These rough divisions correspond to general features of the topography, soil types, water availability, and natural fertility, but it should be realized that considerable local variation exists throughout the state. Limited areas of the panhandle have relatively impermeable hardpan clay soils that support embankment ponds, which are currently the most productive for raising catfish in the state. Many areas of peninsular Florida have widely-fluctuating water tables and relatively porous substrates and are not suitable for embankment ponds; standing fresh waters in these areas are generally in

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Catfish Farmin g in Florida Pa g e 12Februar y 1999 Figure 9 Racewa y culture s y stem.the form of natural solution lakes, swamps, and excavated orprovisions should be made to allow for complete draining of leveed ponds. The diversity of soil types and vegetation inthe pond for harvesting and prior to stocking. Harvesting peninsular Florida results in considerable variation betweenwill also be easier if there are no stumps, logs, and debris sites with respect to nutrient availability and pr oductivity.present. The pond must have an a cceptable sp illway and Because of the diversity of geological and climaticpipe can be fitted with a sleeve of larger pipe and the conditions throughout the state, it is impossible to providesp illway s hould be wide enough so that the maximum flow uniform guidelines for pond construction in Florida. Beforeis less than 3 inches deep in order to prevent fish from attempting to construct a pond, one should make a carefulescaping. In extremely permeable soils, plastic or rubber assessment of the topography, soil, water availability andp ond sealants or liners may be used to eliminate water loss chemistry, nutrient content, and other physical features of thefrom seepage, but use of such sealers can be relatively proposed site to determine the most appropriate type of pondexpensive for larger ponds in terms of installment costs for for the area. In general, traditional embankment pondslabor and materials. Some ponds and natural lakes, formed by damming streams or runoff areas in slopingparticularly in central and northern Florida, are poor in valleys, ravines, or other hilly terrains are possible mainly innutrients and have relatively low pr oductivity. Artificial northwest Florida. In other regions of the state, ponds thatfer tilization of these waters to improve pr oductivity and are most promising for catfish culture would be of theenhance food availab ility is generally not recommended, due excavated or leveed type. Your Soil Conservation Serviceto associated problems with weed control and oxygen levels. (SCS) District Conservationist and other specialists shouldFeeding catfish with prepared feeds is strongly encouraged be consulted for resource analysis, planning assistance, andto promote optimal growth and eliminate the need for standards, regulations, and specifications pertaining to pondsupplemental fertilization of a p ond. construction. A few general recommendations should be followed when considering building a catfish pond for commercial production. (Figure 9) Because of weed control, high water temperatures, and other management problems, large ponds would generally be more difficult to use for catfish culture in Florida. Consequently, ponds in the 1/10 1/4 acre size range are suggested for use. The depth of the p ond should be planned so that there will be a minimum water depth of 4-6 feet during the driest time (survey in April or May). This may mean that a basin depth of 8-12 feet is needed in regions where water levels fluctuate widely. Much greater depths are discouraged because of the danger of oxygen depletions during hot weather. Ponds should have gently sloping basins and well-vegetated shorelines to prevent erosion. If possible, overflow drain if runoff discharge is expected. The overflowAlternative FacilitiesBecause of various constraints that limit the efficiency and desirability of constructing p onds in many areas of Florida, use of other facilities may provide great potential for raising catfish in certain regions. Raceway systems have been successfully used by some producers, although they require more intensive management than pond culture. Raceways consist of series of long, narrow earthen or concrete channels through which there is a continuous flow of water. They may be either open systems, in which water flows through the raceways and waste treatment fac ility without recycling, or closed systems, in which water is recycled through an aux iliary storage reservoir, the raceway, and the waste treatment pool. Raceways require a ubiquitous supply of high-qua lity water. Construction of raceway systems should be done under the supervision of experienced professionals, due to their complex design and operation. They should be trapezoidal or parabolic in cross section, with bottom widths of 4-15 feet and a grade of 1-3 feet per 100 linear feet (1-3% slope). Each section should be no more than 100 feet l ong (sections may be constructed in series by installing earth or concrete check dams or bulkheads at the lower end of each section). Water depth should be about 3 feet at the upper end and 4 feet at the lower end of each section. A settling basin (la goon) is built below the last section of a raceway to collect organic wastes. Size and depth of the lagoon must be determined after considering the number of sections to be installed and the size of the water reservoir. The lagoon should be wider and deeper than the raceway sections so that water movement

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Catfish Farmin g in Florida Pa g e 13Februar y 1999 Figure 10. Floatin g ca g es can hold catfish for g rowout where traditional pond culture is not practiced.will be slow e nough to allow suspended wastes to se ttle, and should be drained and cleaned after each crop of fish is harvested. Cage culture of catfish represents a second potentially good alternative to p ond culture in Florida but s till lacks the technology that provides all growers with consistent results. Some of the advantages to this method are: (1) cages can be put in many types of water, such as ponds, lakes, canals, borrow pits, etc., some of which might not otherwise be especially suitable for aquaculture; (2) cages allow for a combination of cultures in ponds, such as raising catfish in cages with bass and bream in open water; (3) cages can be used to rear small fish to large enough sizes to escape predation before releasing into a pond; and (4) cages allow for easy and complete harvest, by either removing fish all at once or periodically. The major disadvantages of using cages are that (1) fish are under a great deal of stress and may succumb to diseases and parasites more easily if they are crowded; (2) treatments for diseases are more difficult to administer; (3) feeding management of caged fish must be relatively intense; and (4) poaching becomes easier. Cages are made of vinyl-coated wire, polyethylene, nylon, or other corrosion-resistant mesh on PVC, wood, or metal frames and are suspended freely in the water column. Many cage designs and sizes have been used, but most are 1-2 cubic yards (0.8-1.5 cu. meters) and made of 1/2 inch or larger mesh. Cages may be either cylindrical or rectangular, but the design and placement in the water must allow for a depth of at least 3 feet of water in the cage. Tops of cages are usually made of a solid opaque material, such as plywood or aluminum sheeting, and must have a feeding ring. The feeding ring is an enclosed cylinder of wood, mesh (1/8 inch), or other suitable material attached to the top of the cage and extending about 4 inches above the top and 12-16 inches beneath the water surface. Producers generally give caged fish floating feeds, which should be placed within the feeding ring to insure that food does not pass outside of the cage. Cages may be attached to metal or wooden stakes or piers in an open body of water, or they can be floated using Styrofoam pontoons, plastic bottles, or other bouyant materials. They should be floated with the lid about 3-6 inches above the water and with at least 12-36 inches between the cage and the bottom of the pond or lake, so that fish wastes are adequately dispersed. Cages should be placed at least 10 feet apart. It is important to frequently check caged fish for signs of stress, infections, and parasites and to treat them accordingly if necessary. Clean cages periodically to remove growths of filamentous algae.(Figure 10)Water QualityAs with hatching fry, the rearing of food-sized fish depends vitally on good water qua lity. The most important water quality characteristics include dissolved oxygen, temperature, pH, total alkalinity, and total hardness. Standard instruments and kits for measuring these parameters are available through commercial suppliers. Water quality s hould be checked once per day around sunrise. The pH of water to be used for catfish culture should be between 6.5 and 8.5. Water that is not in this range can be treated with effective buffering compounds, such as agricultural lime to increase pH, and hydrochloric acid or aluminum sulfate to decrease pH. If the total alkalinity or total hardness of pond water is below 20 mg /liter add lime during the late fall or early winter. Ponds in Florida near limestone or similar sediments ordinarily should require few corrections for total alkalinity and hardness. Growth of catfish is greatest at water temperatures of 80 -85 F (27 -29 C) and is least at temperatures below 60 F (16 C). This translates into a maximum growing season of 200 or more days per year in many areas of Florida. Catfish can tolerate the normal low water temperatures in the state, but their survival, growth, and food conversion may be jeopardized by combinations of high water temperature, low dissolved oxygen, high stocking density, disease, and other chemical and biological interactions. Consequently, Florida farmers should make a special effort to carefully monitor summer water quality and take remedial measures if poor water conditions develop that may adversely affect fish health. Dissolved oxygen concentrations should be measured frequently and maintained above 4-5 ppm. Oxygen levels

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Catfish Farmin g in Florida Pa g e 14Februar y 1999fluctuate widely and may be influenced by factors such as"Transporting Fingerlings"). algal blooms and plant growth, wind, cloud cover, amount of decaying organic sediments, and temperature. Oxygen inThe number of fish to stock depends on many factors, the water is lowest at sunrise and can be low on overcast orincluding water quality, size and efficiency of facilities and rainy days, due to respiration by algae, bacteria, fish, andequipment, length of the growing season, feeding schedule, other organisms, and the lack of oxygen production by algaeand size of fish desired for marketing. In general, fish are and aquatic plants. Algae are the main producers and usersstocked according to the surface area of the water. If fish are of oxygen. Moderate wind action helps to aerate water nearnot to be fed, stocking densities in p onds should not ex ceed the surface, but strong winds may stir up oxygen-deficient 100-200 fish per surface acre. Fingerlings (4-8 inches) can sediments and cause low oxygen levels throughout the water.be stocked in p onds at dens ities of 1,000-3,000 or more fish To reduce stress and physical harm to fish from low oxygen,per acre and harvested in one to two seasons if feeding is a successful producer must measure oxygen often, takeplanned. Raceways can be successfully stocked with as many preventive measures, and have emergency aerationas 2,000 fingerlings per 100 foot section when optimal water equipment available. A variety of aeration devices are on theconditions exist. Initial stocking densities of 12 fingerlings market or can be built with relative ease, ranging fromper cubic foot of cage are possible. Regardless of the tractor-propelled paddlewheel aerators to floating,facilities used and degree of management intensity, lower electrically-powered models. Pond owners can further reducestocking densities reduce risk of losses to oxygen shortages, problems associated with low oxygen by aerating incomingparasites, and infectious diseases. Fewer fish should be water if necessary and maintaining a proper algal bloom bystocked in waters that may become very hot in the summer or not overfeeding the fish.that have excessive water quality and weed problems. Higher Water should never contain pollutants or toxicants.not fed at the same rates as fish stocked at lower dens ities. Certain metals, pesticides, and other compounds can beWater qua lity becomes limiting at high feeding rates. extremely toxic to fish. Galvanized equipment may releasePrudent managers are aware of the limits of their facilities, enough zinc to k ill catfish, and copper toxicity may resultequipment, and water c onditions and stock fish at densities from use of copper-based pipes and other materials. It is bestthat are appropriate to their harvest goals. to use plastic pipes, coated screens, and other nonmetal equipment whenever possible. Catfish are very sensitive to chlorine, so treated municipal water (usually containing < 2 ppm chlorine) should only be used if first dechlorinated with 7 ppm sodium thiosulfate to 1 ppm chlorine. Pesticides must always be used with extreme caution. Salinity concentration of water is of special concern to farmers drawing their water supplies from coastal areas. Channel catfish can withstand salt in small amounts, but salinity should be checked if high levels are suspected. Channel catfish can tolerate salinities up to 12 parts per thousand (o/oo), but they w ill not breed if the level is over 7 o/oo (full strength sea water is about 30-35 o/oo). Higher salinity levels may result in physiological stress. Avoid abrupt changes between fresh and salty water.StockingCatfish can be stocked in the late fall, winter, or early spring. Summer stocking must be avoided since high water temperatures and low oxygen in hot weather greatly increase stress and the possibility of death due to suffocation, disease, and other factors. If possible, avoid moving or handling fish in the afternoon and avoid drastic changes in water temperature. Fingerlings for stocking should be moved as quickly as possible in well aerated containers (see stocking densities result in smaller fish at harvest if they areAcclimating FingerlingsBefore stocking fish in a pond or other rearing area, adjust the water temperature and other water quality factors in the fingerling transport tank to match the pond water. This should be done by gradually transferring small amounts of water from the pond into the hauling tank un til the tank water temperature equals that of the pond. Catfish can generally withstand a change of 10 F if the water is tempered over several minutes. For greater temperature differences, one must be very careful to slowly equalize water temperatures before moving fingerlings from the transport tank to the pond. It is best to adjust water temperature about 1 ( F every ten minutes. Improper acclimation can directly cause fish to die from temperature shock. If fish are not killed by the shock, they may be weakened and become more susceptible to infectious diseases and parasites.FeedingCatfish grown at high densities require a nutritionally complete feed to maximize growth and maintain good health. Commercially-prepared feeds should contain all essential nutrients and consist of 32-40% protein. Floating pellets or a combination of sinking and floating pellets are desirable in

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Catfish Farmin g in Florida Pa g e 15Februar y 1999most situations. Fingerlings less than 6 inches should bebe resistant to or tolerant of pathogenic organisms if poor given pellets smaller than 3/16 inch (Table 3). Fish over water quality and stressful c onditions are minimal. At the pound can be fed 3/16 -3/8 inch pellets. F ood must be storedother extreme, some catfish diseases may be highly in cool, dry areas to reduce mold and loss of nutrients thatcontagious and debilitating, including those that directly may result from excessive heat. Maximum storage time forcause or contribute to fish death. Other organisms that are feeds is usually 4 to 6 weeks.not as intimately associated with the fish, such as aquatic Food should be distributed at the same locations and atfish health under adverse conditions. the same time once or twice each day. Do not feed at night, since oxygen requirements of fish increase after feeding andBecause of the variety of diseases and pests that afflict oxygen levels in the water normally decrease at this time.catfish, and the variable conditions with which they may The mid-morning or early afternoon hours are good times tooperate, comprehensive and uniformly-applicable feed. Make sure that food is a ccessible to all fish byrecommendations for their control cannot be made. The best distributing it over broad areas and along upwind shorelines.way to ensure good fish health is to prevent unfavorable Do not overfeed since uneaten food can foul the water.biological cond itions from developing, by carefully Conversely, avoid underfeeding because it can result in poormonitoring all aspects of an aquaculture system, and to health, lower growth rates, and greater size variation ofquickly isolate, identify, and properly treat any disease or harvested fish. Observe feeding activity to make sure that allpest problems that arise. A successful manager becomes food is consumed in about 10 to 20 minutes.fam iliar with procedures of identifying, preventing, and/or Recommended feeding allowances for catfish are basedlaboratories or specialists when dealing with unknown on a percentage of the body weight or standing crop weight.problems. Be sure to check local regulations governing the Since the conversion efficiency of f ood is influenced by manyuse of chemicals when treating culture systems with factors, such as stocking density, water quality, temperature,herbicides, pesticides, or medications. and fish size, suggested feeding rates are only approximate guides and the producer must exercise good judgement inFor more detailed information concerning disease establishing a feeding program. Ideally, fish cultured foridentification and control, consult Florida Extension Circular food should be fed 1-3% of their weight at least once per day 716, "Introduction to Fish Parasites and Diseases and Their during the growing season. Avoid feeding more than 35Treatment." pounds per acre per day in hot weather unless emergency aeration is available. Feeding allowances must be increased as fish grow. Often this is done by feeding as much as the fish will eat each day wit hout leaving excess food floating on the water. Alternatively, standing crop weight can be estimated weekly to make appropriate adjustments in the amount to feed. Estimate crop weight by removing a small sample of fish, weigh them, and multiply the average weight of individuals in the sample by the total number of fish present in the pond. Catfish held over winter should be fed sinking pellets at about 1% of their weight every 2 to 3 days when water temperature is below 65 F (18 C). Feeding rates should be reduced by 50% or more during very hot weather (water temperature > 85 F) and on rainy or overcast days. However, if aerators are available and fish are to be commercially produced, they s hould be fed to near satiation. Otherwise, fish will grow too slowly and return on investment may be too low to be profitable.Disease and Pest ControlCatfish are susceptible to a large array of parasites andindicate a possible disease problem include: (1) a reduction disease organisms, as well as being affected by a host ofor cessation of feeding; (2) erratic or lethargic swimming; (3) other plant and animal pests. In many cases, healthy fish mayschooling just below the surface; or (4) swimming or plants and algae, may contribute directly or indirectly to poor treating common pest agents and consults with diagnosticDiseases and ParasitesThe large number of microscopic diseases and larger parasites that infect catfish range from those that are relatively benign and generally not harmful under normal conditions, to those that cause high mortalities and have no effective treatments. A good disease management program consists of precautionary measures to ensure clean water and healthy environmental conditions. Stress plays a major role in lowering the resistance of fish to pathogens, and all factors that may contribute to stressful conditions must be kept minimal. These include maintaining adequate oxygen levels, avoiding extreme temperatures, and handling or moving fish as little as possible. Chemicals s hould be used to treat disease outbreaks only when preventive measures have failed, and it is essential that appropriate medications be administered in proper dosages for treating specific diseases. For this reason, early detection and correct diagnosis of disease organisms is imperative if chemotherapy is to be successful. Some of the behavioral signs that may

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Catfish Farmin g in Florida Pa g e 16Februar y 1999 Figure 11. Seine harvestin g of lar g er ponds can be mechanized with a modest crew.scraping against the substrate or objects in the water.filamentous algae can often be controlled with triploid grass Physical signs that diseased catfish may exhibit include: (1)carp, again under the supervision of the Florida Game and excessive mucous production; (2) abnormal colorationFreshwater Fish Commission. Large phytoplankton blooms (lighter or darker, grayish or bluish, etc.); (3) erosion orare not practically controlled, even with copper compound fraying of the fins or skin; (4) sores, hemorrhages, or unusualherbicides. When excessive blooms occur, monitor dissolved growths on the body or fins; (5) swollen, eroded, or paleoxygen frequently and be prepared with emergency aerators. gills; (6) a swollen abdomen f illed with a cl oudy, clear, orAlso, reduce nutrients that promote blooms by decreasing the bloody fluid; or (7) bulging of the eyes (exophthalmia). If anlevel of feeding. infectious disease or parasite outbreak is suspected, quick action should be taken to isolate, identify, and treat if necessary. Some individuals and laboratories diagnose fish diseases and recommend treatments, but unfortunately there are few diagnostic centers in Florida that provide these services. If diseased fish are to be sent to a laboratory for inspection, live fish showing symptoms of the disease should be selected and shipped alive in cooled bags or packed freshly on ice. Be sure to notify the laboratory that you are sending fish and give them any necessary information that may be helpful in identifying or treating the disease.Weed Control Harvest ing and Pro cessingExcessive algal blooms or rampant growths of aquatic plants can be detrimental to catfish by causing oxygen depletions, and may impede harvesting and reduce available habitat. In Florida, exotic plants such as hydrilla, water hyacinth, and water pennywort can become extremely dense and cause acute problems. A moderate growth of aquatic weeds generally does not present a major problem in catfish ponds, but dense infestations should be avoided. Weeds that become a nuisance must be correctly identified and properly controlled using aquatic herbicides or biological agents. Approved herbicides must be used with caution, following specific recommendations and restrictions stated on the label. Stocking of hybrid grass carp, Tilapia or other herbivorous fishes to control aquatic weeds should be done under the supervision of the Florida Game and Freshwater Fish Commission. Microscopic algae that are suspended in the water play a beneficial role in the ecology of a pond by providing food to invertebrates, eliminating some organic wastes, and producing oxygen thr ough photosynthesis. A healthy pond should have a moderate level of planktonic algae to keep conditions in balance. A proper algal bloom can be measured by lowering a white object, such as a painted board, into the water. If the water is not stained from organic compounds, the board should be visible to about 2-4 feet beneath the surface. If the water is excessively turbid, has a distinct green color, or a white object cannot be seen more than a few inches below the surface, algae could be too dense and there may be a danger of oxygen depletions at night. Extremely dense growths of algae are cause for concern. AttachedOther PestsFlorida catfish producers should be aware of other potential pests that may negatively affect catfish survival or health. Flying forms of fire ants can kill fish if they are ingested, and should be controlled with appropriate pesticides. Alligators, some snakes, and other predators that may eat fish should be kept out of rearing facilities by using fences or other structures. Farmers that use surface water supplies should prevent wild fish from entering catfish p onds by screening or filtering all inlet pipes, streams, etc. Catfish stocked as fingerlings in the early spring should attain at least one pound by the following fall and can be harvested for consumption. It is generally preferable to harvest most or all of the stocked crop in a pond in one season unless larger dressed fish are desired. Many producers drain their ponds completely following harvesting and remove organic sediments or allow them to oxidize. Harvesting methods vary between farming operations, depending on the preferences of the producer. Fish are generally removed by seining, trapping, trot lines, or hook-and-line angling. Total harvest is most easily

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Catfish Farmin g in Florida Pa g e 17Februar y 1999 Figure 12. Seine harvestin g small ponds ma y be unmechanized with few people.achieved by seining or trapping, especially if the rearing facility is drained or if fish are concentrated into aMost large-scale pr oducers ship their crops to fish harvesting basin. Seining should be done with a large,processing factories, or have the n ecessary equipment and coated net of 1 1/2 inch mesh. Catching fish by thislabor to process themselves. There are few commercial method w ill be easier if the p ond water is lowered or ifprocessing fac ilities in Florida, so pr oducers in the state fish are coaxed into a harvesting pool or lured near theshould be prepared to process their own crop or possibly seine by feeding them in a prescribed area over severaltransport them relatively long distances to processing days prior to harvesting. Catfish can be successfullyplants in other southeastern states. Alternatively, trapped using wooden-slat traps, nylon hoop nets, anddepending on local markets, fish might be sold live at wire-mesh funnel traps. Hook-and-line angling is generallyroadside stands or through fish-out ponds. most popular in stocked catch-out ponds or fee-fishing areas. Harvesting for commercial sale of fish should be done when transport to processing fac ilities will be immediate. Do not feed fish for one day prior to harvesting. (Figure 11), (Figure 12). Catfish are processed by removing the head and spines, skinning and eviscerating the fish, washing, and thoroughly packing them on ice. Properly dressed fish packed in ice can be held for up to 6 days if they are to be marketed fresh. Fish to be frozen should be wrapped in plastic bags or airtight containers and immediately frozen (frozen fish should not be held for more than a few months). Before marketing your product, prepare and taste a representative sample of the fish crop. If any off-flavor is detected, the fish should not be sold for public consumption.Table 1 Recommended brood fish diet. In g redient Percent of Total So y bean meal ( 44% protein ) 50.5 Ground corn 14.93 Wheat shorts 6.0 Distillers dried solubles 7.5 Fish meal 15.0 Animal fat 3.0 Pellet binder 2.5 Dicalcium phosphate 0.5 Vitamin premix 0.75 Coated vitamin C 0.057 Trace mineral mix 0.075 Anal y sis: Total crude protein 35.6% Di g estible ener gy 2640 kcal/k g Ener gy to protein ratio ( kcal/ g) 7.3 : 1.0

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Catfish Farmin g in Florida Pa g e 18Februar y 1999 Table 2 General characteristics used to estimate the a g e of channel catfish e gg s. E gg Appearance Approximate A g e ( 78 F ) Estimated Da y s to Hatchin g 1No Pulsations < 24 hours 7-8 Pulsatin g motions 1-2 da y s6 7 Faint blood y streak 2-3 da y s5 6 Blood throu g hout e gg 3-4 da y s4 5 E y es visible 4-5 da y s3 4 Entire fish visible, embr y o occasionall y twists or moves 5-6 da y s2 3 No blood y streaks 6-7 da y s1 2 Hatchin g be g ins 7-8 da y s0 1 For ever y 2 F above or below 78 F, subtract or add one da y to hatchin g time, respectivel y 1Table 3 Optimum feed particle size for catfish fr y and fin g erlin g s. Fish size ( inches ) Particle Size ( millimeters ) < 0.5 0.42-0.60 0.5-1.0 0.60-0.84 1.0-1.5 0.84-1.19 1.5-2.5 1.19-1.68 2.5-4.0 1.68-2.38 4.0-6.0 2.38-3.36 > 6.0 3/16 inch pellet Table 4 Estimated fin g erlin g size after 120 to 150-da y g rowin g season under different stockin g re g imes. Optimal mana g ement techni q ues are re q uired to attain these y ields. Fr y Stockin g Densit y ( fish per acre ) Avera g e Len g th ( inches ) 10,000 7-10 30,000 6-8 53,000 5-7 73,000 4-6 95,000 3-5 120,000 3-5 140,000 3-4 200,000 2-3 300,000 1-2 500,000 about 1 Table 5 Su gg ested feedin g fre q uencies and allowances for fr y and fin g erlin g s at different temperatures. Water Temperature ( F ) Feedin g Allowance ( % bod y wei g ht/da y) Feedin g Fre q uenc y > 87 2 2 times/da y 80-86 6 4 times/da y

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Catfish Farmin g in Florida Pa g e 19Table 5 Su gg ested feedin g fre q uencies and allowances for fr y and fin g erlin g s at different temperatures. Water Temperature ( F ) Feedin g Allowance ( % bod y wei g ht/da y) Feedin g Fre q uenc y Februar y 1999 68-7932 times/da y 58-67 2 1 time/da y 50-57 2 alternate da y s < 50 1 ever y 3-4 da y s Table 6 Seine mesh sizes and g rader bar widths used for separatin g size classes of fin g erlin g s. Smallest Fish Len g th ( inches ) Seine Mesh ( inches ) Grader Bar Spacin g inches millimeters 3 1/4 27/64 10.7 4 3/8 32/64 12.7 5 1/2 40/64 15.9 6-7 3/4 48/64 19.1 8-10 1 125.4Table 7 Recommended loadin g densities for haulin g fin g erlin g s. Densities are for water temperature at 65 F and ideal aeration; reduce numbers b y 25% for each 10 F rise in temperature. Number of Fish per pound 8 hrs 12 hrs 16 hrs Transport time ( hours ) Load Densit y ( pounds fish/ g allon water ) 1 6.3 5.6 4.8 2 5.9 4.8 3.5 4 5.0 4.1 3.0 50 3.5 2.5 2.1 125 3.0 2.2 1.8 250 2.2 1.8 1.5 500 1.8 1.7 1.3 1,000 1.3 1.0 0.7 10,000 0.2 0.2 0.2