SRAC Publication No. 181

February 2008 VI PR Revision Feeding Catfish in Commercial Ponds

Menghe H. Li 1 and Edwin H. Robinson 1

Since feeding is the most impor - to meet the fishes’ total nutritional motes total consumption to avoid tant task in the intensive pond requirements for normal growth waste and higher production cost. production of catfish, the person and development. All catfish feeds Catfish feeds are available as meal responsible for feeding should be are manufactured commercially; (powder), crumbles, and floating an experienced fish culturist who none are prepared on the farm. or slow-sinking pellets. Sinking can tell whether or not the fish are Manufacturers usually produce feeds (prepared in a pellet mill) feeding normally by observing “least-cost” formulations rather are seldom used in catfish produc - them as they come to the surface than “fixed-formula” feeds. In tion. Some producers use sinking to feed. This is generally the only least-cost feed formulation, the medicated feed containing oxyte - time the fish can be seen during formulas vary as ingredient prices tracycline because the antibiotic is grow out. Feeding behavior can be change. However, there are several sensitive to the high heat used in an important clue to the general limitations in the manufacture of the manufacture of floating feeds. health of the fish and the pond catfish feed using least-cost formu - However, there are now floating environment. If the fish are not lations. oxytetracycline-medicated feeds feeding normally, the person who made with “cold-extrusion” tech - is feeding must inform the farm • There is a relatively small num - nology. ber of suitable feedstuffs. manager that there may be a prob - The size and form of feed to use lem. Feed cost is the largest oper - • There is a general lack of depend on fish size, water temper - ating expense in catfish produc - knowledge about the nutrient ature and the type of management tion, so fish should be fed a nutri - levels that result in maximum used. Meal feeds are used in tious feed in a manner that results profit as opposed to maximum hatcheries and nursery ponds dur - in fast growth and efficient feed weight gain. ing the first 3 to 4 weeks of fry conversion without degrading • Feed mills lack the storage culture. When fry grow to about 1 water quality. Because feeding is capacity to house a large num - to 2 inches and come to the sur - influenced by a number of uncon - ber of different ingredients. face seeking food, they are fed trollable factors and because the 1 Examples of feed formulations small floating pellets ( ⁄8 inch in environment in each pond is dif - diameter) or crumbles. Floating ferent, there are no standard feed - used to grow catfish at various life stages are given in Table 1. feed is generally preferred because ing practices in the catfish indus - it makes feeding behavior much try. The following recommenda - Form and size easier to monitor. tions are guidelines. In commercial food fish produc - Feeds must not only contain all 5 3 Feed formulations tion, floating feed pellets ⁄32 to ⁄16 essential nutrients, but must also inch in diameter are usually used. be palatable and of a size that can Feeds used in commercial catfish In multiple-batch cropping sys - be readily ingested. If fish don’t production must contain adequate tems, where various sizes of fish eat it, or cannot eat it, maximum amounts of all essential nutrients are present in a pond, it would be growth is not achieved and the desirable to use multiple feed producer loses money. The feed 1 sizes, but this is not practical in Thad Cochran National Warmwater Aquaculture must be offered in a way that pro - Center, Mississippi State University. large-scale operations. Slow- Table 1. Examples of feed formulations used to culture catfish. % of feed Ingredient Fry feed Fingerling feed Food fish feed (50%) a (35%) (32%) (32%) (28%) (28%) (26%) Soybean meal (48%) a – 44.2 41.6 47.0 30.1 35.4 28.3 Cottonseed meal (41%) – 10.0 10.0 10.0 10.0 10.0 5.0 Menhaden meal b (61%) 74.2 8.0 4.0 – 4.0 – 4.0 Corn grain – 27.6 32.1 30.3 33.6 31.9 35.3 Wheat middlings 20.4 7.5 10.0 10.0 20.0 20.0 25.0 Dicalcium phosphate c – 0.5 0.6 1.0 0.6 1.0 0.7 Catfish vitamin mix d include include include include include include include Catfish mineral mix d include include include include include include include Fat/oil e 5.0 2.0 1.5 1.5 1.5 1.5 1.5 a Values in parentheses represent the percentage protein. b Other animal proteins can be used to replace menhaden meal. c Phytase enzymes can be used to replace dicalcium phosphate. d Commercial mixes meet or exceed all requirements for channel catfish. e This is sprayed on finished feed pellets to reduce feed dust (“fines”) . sinking feeds are often used dur - catfish are generally fed once daily Factors affecting ing the winter when low tempera - to what is commonly called satia - feed conversion tures make catfish reluctant to tion (that is, feeding the fish all they come to the surface. Using a slow- will eat in about 20 to 30 minutes). Feed conversion ratio (pounds of sinking feed at this time gives fish Since catfish feeding activity varies feed fed per pound of weight gain) a better opportunity to feed. with fish size and age, water tem - is a production term used to mea - Antibiotic-medicated feeds are perature, water quality, and fish sure how efficiently fish convert the available as small and large float - health status, producers must feed to body mass. The lower the ing pellets to treat bacterial infec - decide each day how much and ratio, the better the feed is being tions. how often to feed. No two ponds of used by fish. In commercial catfish production, the feed conversion Factors affecting fish are exactly alike; as a result, feeding behavior may differ greatly ratio dramatically affects the prof - feeding practices from pond to pond and from day to itability of the farm. The higher the feed conversion ratio, the higher Feeding is a highly variable day. Under normal conditions, cat - fish should be fed daily as much production cost will be (Table 2). process among catfish producers. For example, at a feed price of $250 Some producers use computer pro - feed as they will consume without adversely affecting water quality. per ton, it takes 25 cents worth of grams that determine feeding rate feed to produce 1 pound of fish if based on a percentage of fish body However, depending on water tem - perature, water quality and the the feed conversion ratio is 2, while weight. Feeding a prescribed it costs 38 cents (a 50 percent amount of feed based on fish bio - health of the fish, sometimes it may be better to restrict the daily feed increase) at a feed conversion ratio mass in a particular pond works of 3. best when the biomass in each allowance or to feed less frequently. pond is known and a fairly accu - Most commercial ponds are relative The feed conversion ratio of catfish rate estimate of feed conversion large (usually 10 acres or larger). It is influenced by feed quality, fish can be made. However, since most is important that the feed be blown size, feeding rate and frequency, catfish producers remove only over a large area to make it accessi - stocking density, water temperature market-size fish and replace har - ble to as many fish as possible. It is and water quality. Fish size appears vested fish with fingerlings, it is better to feed on all sides of the to have a marked effect on feed difficult to know the biomass after pond, if wind conditions allow. If conversion. As fish grow larger, the several harvests and restockings. the wind is blowing, feed must be feed conversion ratio greatly In fact, many catfish producers distributed along the upwind side of increases. For example, in small estimate their inventory by the the pond to prevent it from washing experimental ponds, it takes 1.8 amount of feed fed. As a result, ashore. pounds of feed to grow 1 pound of Table 2. Feed cost in cents per pound of catfish produced at different pounds per acre per day. The total feed conversion ratios and feed prices. feed input, net production, weight gain and feed conversion were Feed price, dollars/ton about the same when fish were (cents/pound in parenthesis) fed to apparent satiation or fed at Feed conversion 200 225 250 275 300 325 a “cut-off” rate of 120 pounds per ratio (10.0) (11.25) (12.50) (13.75) (15.0) (16.25) acre per day. Generally, the higher the stocking density, the lower the 1.5 15 17 19 21 23 24 feed efficiency will be, but this 1.6 16 18 20 22 24 26 may be due partly to poorer fish survival at higher densities. 1.7 17 19 21 23 26 28 Unfavorable environmental condi - 1.8 18 20 23 25 27 29 tions, such as temperature extremes, also can lower feed effi - 1.9 19 21 24 26 29 31 ciency. 2.0 20 23 25 28 30 33 Warm weather feeding 2.1 21 24 26 29 32 34 Fry and fingerlings 2.2 22 25 28 30 33 36 2.3 23 26 29 32 35 37 When stocked into nursery ponds, catfish fry are tiny and are weak 2.4 24 27 30 33 36 39 swimmers. They cannot move 2.5 25 28 31 34 38 41 rapidly to areas where manufac - tured feeds are offered, which 2.6 26 29 33 36 39 42 makes feeding difficult. The best 2.7 27 30 34 37 41 44 way to ensure good growth and survival of newly stocked fry is to 2.8 28 32 35 39 42 46 make sure that plenty of natural 2.9 29 33 36 40 44 47 food is available in the nursery 3.0 30 34 38 41 45 49 pond when the fish are stocked. Natural foods for catfish fry 3.5 35 39 44 48 53 57 include large zooplankton (micro - 4.0 40 45 50 55 60 65 fish when the fish are raised from 1 ⁄2 pound to 1 pound (Fig. 1). However, if the fish are raised 4 1 from 2 to 2 ⁄2 pounds, 2.9 pounds ◆ of feed would be needed to grow ◆ 1 pound of fish. Larger fish use more energy for sexual maturation 3 o and reproduction than for growth, i ◆ t a

which increases the feed conver - r ) sion ratio. n ◆ n o i i a Theoretically, the best biological s r g

/ 2 feed conversion ratio occurs when e ◆ d v

e ◆ fish are fed to or near satiation. n e o f ( However, in production ponds c d

satiation feeding usually leads to e poorer feed conversion than that e F 1 seen in restricted feeding pro - grams. This is mainly because more feed is wasted when fish are fed to satiation daily. Research with food fish demonstrates that 0 feeding to satiation daily results in 0 1 2 3 4 greater production and weight gain, but causes the feed conver - Fish size (pound/fish) sion ratio to be higher than when fish are fed no more than 80 Figure 1. Relationship of fish size and feed conversion ratio for pond-raised channel catfish. Data are from a feeding study conducted with small experi - mental ponds. scopic crustaceans), insect larvae much of the feed’s nutrient value term, average daily feeding rates and insects. Zooplankton and (especially micronutrients such as should not exceed 120 to 150 insects eat plant material in the vitamins and minerals) is probably pounds per acre. pond, so to produce them in abun - lost because of the extended time On a large farm, the feeding time dance you must increase natural the pellet is in contact with the is mainly dictated by the large plant production by fertilizing the water. number of ponds that must be fed pond before fry are stocked. For Food fish in a limited time. Studies conduct - pond fertilization guidelines, see ed at the NWAC show no advan - “Optimizing Fry Pond Commercial feeds for food fish tages to feeding at a certain time Fertilization” by Charles Mischke generally contain 28% or 32% pro - of day. There were no differences and Paul Zimba (National tein. A 26% protein feed is also in weight gain, feed consumption Warmwater Aquaculture Center available from some feed mills. and feed conversion among catfish [NWAC] News, Vol. 6, No. 1, 2003, Research has shown that protein fed to satiation at 8:30 a.m., 4:00 http://www.msstate.edu/dept/tcnwac/ levels as low as 24% can support p.m. and 8:00 p.m. No differences Vol06No1Oct2003.pdf ). maximum growth if fish are fed as in aeration time were noted either. Even though fry presumably meet much as they will eat. Low-pro - However, feeding near dark or at their nutrient needs from natural tein feeds cost less, but usually night is not recommended for food organisms, they are fed once result in more body fat and lower large commercial ponds unless or twice daily with a finely ground processed yield. Research has sufficient aeration is available. feed at a rate of 10 to 30 pounds shown that there is a marginal dif - The fishes’ peak oxygen demand per acre per day. Fry feed may be ference in the processed yields of occurs about 6 to 12 hours after a secondary food source, as well fish fed a 28% or 32% protein feed feeding. If fish are fed at night, as a fertilizer to keep the pond fer - (about 0.3 to 0.4 percentage unit peak oxygen demand will occur tile, so it is not necessary to feed a reduction in fish fed the 28% pro - when dissolved oxygen levels are high-protein feed as is used in the tein diet), but the difference may low. In cool weather (late fall, hatchery. Fines from regular 28% be significant to catfish processors. winter and early spring), water or 32% protein feeds for food fish The type of feed to choose temperature is usually higher in are suitable for catfish fry during depends on whether fish prices the afternoon and fish will eat bet - this phase. Some catfish producers are based on live weight or on ter then. During warm weather, do not feed the flour-type feeds, processed yield. Although fish fed many catfish producers start feed - preferring feed crumbles or float - higher protein feeds (35% to 40%) ing early in the morning as soon ing pellets that, though largely have better processed yield and as dissolved oxygen levels begin to uneaten, break up in the water lower body fat content, these increase. This appears to work and help keep the pond fertile. feeds usually are not economical. well. After a few weeks, the fry will Several factors influence how Feeding once daily is usually satis - have grown into fingerlings 1 to 2 much to feed in a production factory for food fish grow out. inches long and will come to the pond. These include fish size, Research has shown that feeding pond surface seeking food. standing crop (number and weight twice daily is not necessarily ben - Small fingerlings are typically fed of fish present in the pond), water eficial because the increased once or twice daily to satiation temperature, water quality and amount of feed was not complete - 1 using small floating pellets ( ⁄8 inch weather conditions. Food fish are ly converted into weight gain. It is in diameter) or crumble feeds con - typically fed daily to apparent sati - likely that feeding twice daily taining 32% or 35% protein. Part ation without adversely affecting increases the feed conversion ratio of this ration is fish meal. water quality. Feeding as much as because over-feeding can waste Research shows that when finger - the fish will eat is especially feed if the feeder is not careful. lings reach about 4 inches in important in a multiple-batch During the growing season, most length, a 28% protein feed is suffi - cropping system because it gives food fish producers feed seven cient for maximum growth. the smaller, less aggressive fish days a week, although some feed Feeding twice daily may improve more opportunity to feed. six days a week. Research con - fingerling weight gain and produc - However, feeding to satiation is ducted at the NWAC, using a tion. Some producers feed finger - not an easy task because it is diffi - single-batch cropping system, lings the same feed they feed to cult to determine when the fish showed that feeding fish to satia - food fish. Fingerlings consume are satiated. Thus, it is easy to tion six days a week (not feeding large feed pellets by nibbling on overfeed, which wastes feed and on Sundays) reduced net produc - the feed after the pellets soften may cause water quality problems. tion by 3.3 percent, compared and begin to break up in the Feeding rates should not exceed with fish fed seven days a week. water. Fingerlings appear to grow what can be assimilated by Feeding five days a week (not well with this feeding method, but microorganisms in the pond. Long- feeding on both Saturdays and a maintenance ration daily or by should be an extruded feed (slow- Sundays) further reduced net pro - feeding to apparent satiation once sinking) and not a feed made duction (by 6.9 percent). The feed or twice a week. Since fish of vari - through a pellet mill. Extruded conversion ratio was reduced by ous sizes are usually present in a feeds are more stable in water and 4.8 percent for fish fed six days pond at the same time, it is better will remain intact longer than a and by 7.9 percent for fish fed five to feed all they will eat on days feed prepared in a pellet mill. days a week. When you consider fed than to feed a little every day. all factors (a slight decrease in net Feeding the fish all they will eat Summary production, slight improvement in on the days fed will allow the Feeding catfish is more an art than feed conversion, and possible smaller, less aggressive fish to a science. There is no best feeding reduction in other costs associated feed. Based on research at the method for the whole catfish with feeding), feeding six days per NWAC, it appears that feeding industry because each farm, and week may reduce production cost. once a week to satiation can main - even each pond on the same farm, However, feeding only six days tain the body weight of food-size is different. To maximize profits, per week is not recommended if catfish in a single-batch cropping producers must decide what type feed is restricted rather than system. However, feeding more of feed and feeding method are offered to satiation because the frequently will improve the body best for their particular operations. restriction will further reduce fish conditions of the fish. The bottom line is economics. production. This is also true for a Factors to consider are fish price, multiple-batch cropping system, Winter feeding feed price, and whether the prod - since the smaller fish may have Unlike warm-blooded animals, cat - uct price is based on live weight less chance to feed. fish do not feed consistently when or processed yield. Here are gen - Feeding less frequently than daily water temperatures are below 70 eral guidelines for feeding healthy may be called for under certain °F (21 °C ). At water temperatures fingerlings and food fish: circumstances. Research at the of 50 °F (10 °C ) and below, cat - • Feed small fingerlings (less than NWAC has shown that fish fed to fish more or less stop eating. Many 25 pounds per 1,000) a 32% or satiation every other day eat up to producers do not feed during the 35% protein feed twice daily to 50 percent more feed on days fed, winter for various reasons, one of satiation. and fish fed every third day eat up which is that it is difficult to see a to 65 percent more feed, com - positive response from a winter • Feed stockers and food fish a pared with fish fed once daily. feeding program. Research shows 28% protein feed once a day to Catfish are capable of regaining all that winter feeding is beneficial, satiation, but do not distribute or part of the weight they lose though the benefit depends on the more feed than the pond can during a short period of feed severity of the winter. Fish will safely “metabolize” to prevent restriction once full feeding is gain (if fed) or lose (if not fed) water quality problems. resumed. Although there are some more weight during a mild winter • If fish are fed every other day, advantages (lower feed conversion than a cold one. A recent study feed a 32% protein feed to sati - ratio and lower costs for labor and showed that food-size catfish fed ation. aeration) to feeding every other from mid-November to mid-March 1 day or every third day, this prac - • Harvest food fish at 1 ⁄2 pounds gained about 15 percent more for efficient feed conversion if tice is not recommended for rou - body weight, while fish that were tine feeding because the fish fed that size is acceptable to the not fed did not gain or lose weight. processing plant. can not eat enough feed on the There is no precise temperature at days they are fed to make up for which to feed during the winter, • Feed 20 to 30 pounds per acre all the feed missed. Also, feeding but as a general rule, from of a slow-sinking feed once or every other day or every third day November to March when after - twice a week during the winter extends the production cycle and noon water temperatures are 55 to when afternoon water tempera - may reduce processing yield, so in 65 ºF (13 to 18 ºC), feeding about tures are 55 to 65 ºF (13 to 18 the long run it may not be eco - 20 to 30 pounds per acre once or ºC). Feed two or three times a nomical. twice a week appears to be suffi - week when temperatures are Sometimes when fish reach mar - cient. When temperatures are above 65 ºF (18 ºC). ket size but cannot be harvested above 65 ºF (18 ºC), feed two or because of off-flavor or other three times a week. issues that delay harvest, they may Since fish feed less in winter than be fed a minimum amount just to in summer, it is thought that cat - maintain body weight with no fish may respond better to a sink - gain or loss of weight. This main - ing feed than to a floating feed tenance feeding is done by feeding during the winter. Sinking feed SRAC fact sheets are reviewed annually by the Publications, Videos and Computer Software Steering Committee. Fact sheets are revised as new knowledge becomes available. Fact sheets that have not been revised are considered to reflect the current state of knowledge.

The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 2006-38500-16977 from the United States Department of Agriculture, Cooperative State Research, Education, and Extension Service.