Newton, Scott H.

Robison, Walter R.

English

UARK (University of Arkansas )

Journal of the Arkansas Academy of Science Volume 35 Article 28 1981 Ration/Density Comparisons with Caged Channel Catfish Scott H. Newton University of Arkansas at Pine Bluff Walter R. Robison University of Arkansas at Pine Bluff Follow this and additional works at: https://scholarworks.uark.edu/jaas  Part of the Aquaculture and Fisheries Commons Recommended Citation Newton, Scott H. and Robison, Walter R. (1981) "Ration/Density Comparisons with Caged Channel Catfish," Journal of the Arkansas Academy of Science: Vol. 35 , Article 28. Available at: https://scholarworks.uark.edu/jaas/vol35/iss1/28 This article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able to read, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking prior permission from the publisher or the author. This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the Arkansas Academy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu. Arkansas Academy of Science Proceedings, Vol.XXXV,1981 89General NotesMOORE, D.M. 1953. Rediscovery ofbigleaf magnolia in Arkansas.Abstract. Proc. Ark.Acad. Sci. 6:9.SPEAIRS, R. K.,JR. 1976. Ouachita biological station. Proc. Ark.Acad. Sci. 30:83.SMITH,E. B. 1978. Atlas and annotated list of the vascular plants ofArkansas. Univ.Ark.Fayetteville.JEWEL E. MOORE, Department ofBiology, University ofCentral Arkansas, Conway, Arkansas 72032, and INEZHARTSOE (retired), PiggottHigh School, Piggott, Arkansas 72454.RATION/DENSITY COMPARISONS WITH CAGED CHANNEL CATFISH*Caged fish culture as a production method for rearing catfish and trout was first started inthe United States in the late 1%0's and has nowbecome more practical than ever for certain situations (Newton, 1980). This is especially true for the utilization of farm ponds whichare suitablefor cages because the fish cannot be easily harvested otherwise. Since 1967, university and governmental researchers have studied and developedcaged catfish culture for the fish farming industry (Lewis, 1969; Schmittou, 1969; Collins, 1971). They first dealt withculture techniques involvingpotentials and adaptations of the method. They used numerous types ofcages and gradually refined studies to include nutritional trials, stockingsizes and rates, genetics, and fish health (Collins, 1978).Research conducted during the 1970's, primarily in Arkansas and Oklahoma, has further refined cage culture methodology and applicationpotentials (Collins, 1971; Collins, 1978; Newton, 1980; Kilambi et al., 1977). These studies are valuable because they demonstrate the variety ofsituations for using cage culture, the improved feed quality for confined fish culture, and the resource potential for both home and commercialventures.Cages are ideal forevaluating rations for fishdiets (Newton and Dean, 1978; Newton et al., 1980). The need continues for testing availablerations forefficient and economical fish production. This study compares two rations ofsimilar protein levels, 33% and 36%, but quite differentin cost withthree stocking densities ofchannel catfish.A total of 18 cages were stocked withcatfish fingerlings during May 1980. Thecages (0.9m1) were arranged inunits of three across the southend of a 1.6 ha farm pond on the University of Arkansas at Pine BluffAgricultural Research Station as described previously by Newton andMerkowsky (1976). Six cages were each stocked with 200, 350, and 500 fingerlings (average wt. 28 g), respectively, in a randomized pattern.Experimental conditions were triplicated simultaneously for ration and density evaluations. Three cages of each fish density were fed either a36% protein trout ration or a 33% protein catfish ration formulated as floating pellets. Allfish were fed fivedays per week at the rate of4% oftheir estimated body weight, regardless ofdensity or ration combinations.The study period began 14 May and ended on 30 August due to an oxygen depletion whichkilled fish in approximately two-thirds of thecages. Nevertheless, all data were collected from each cage similar tousual harvest operations inprevious studies (Newton et al., 1980). Statisticalcomparisons revealed nosignificant differences between data collected from dead or live fish. Therefore, the relative validity of the assumptionsand determinations reported herein are believed tobe accurate forpractical comparisons among density and ration combinations.Evaluations of the rations and stocking densities were based upon weight gain, food conversion efficiency (FCE), survival, and productioncosts per kilogram of catfish produced. Comparisons between rations revealed no significant differences among net production, FCE, andsurvival. Due to the difference in feed costs (the 33% protein ration was $16/45.5 kg, while the 36% protein ration was $25/45.5 kg) the 33%protein ration was the most cost efficient at allstocking densities (Table 1). With either ration, the cost per kilogram of fish produced was less atthe higher stocking densities (350 and 500 fish); however, production costs were still lower for all densities with the 33% protein catfish ration.The greatest net profit per cage was obtained withthe highest fish density forboth rations.There were significant differences in net production among each stocking density, although survival and FCE were similar (Table 2). Fishstocked at 350 per cage had higher average individual gains than fish stocked at 200 or 500 per cage, whichhad similar average gains. Both FCEand survival were consistently within normal ranges necessary for successful caged catfish production. Survival was unusually high, until theoccurrence of the oxygen depletion. One of the disadvantages of cage culture is that caged fish are more susceptible to oxygen problems than fishinan open pond.Since the fish stocked at 350 per cage had higher individual gains with both rations, it appears that this stocking density was optimum forproducing larger size fish. Fish density considerations have been studied forsome time (Schmittou, 1969; Konikoffand Lewis, 1974), and it hasbeen determined that generally a minimum number of 5-6 fish per 30 cm5 isrequired to avoid behavioral problems. We have used 7-8 fish inmostofour studies; however, the maximum or optimum number to stock deserves further attention. Ahigh quality, less expensive catfish ration out-performed a more expensive trout ration on the basis of fishproduction, economy, and availability.This study was supported withfunds provided by USDA,SEA/CR under PL 95-113.89Journal of the Arkansas Academy of Science, Vol. 35 [1981], Art. 28Published by Arkansas Academy of Science, 198190 Arkansas Academy of Science Proceedings, Vol.XXXV,1981LITERATURE CITEDCOLLINS, C. M. 1978. Catfish cage culture, fingerlings to food fish.Kerr Foundation, Inc.Poteau, OK.22pp.COLLINS, R.A. 1971. Cage culture of catfish in reservoir lakes.Proc. S. E. Assoc. Game and Fish Comra. 24:489-4%.KILAMBI,R. V.,J. ADAMS,A.V. BROWN and W. WICKIZER.1977. Effects of stocking density and cage size on growth, feedconversion, and production of rainbow trout and channel catfish.Prog. Fish-Cult. 39:62-66.KONIKOFF, M. and W. M. LEWIS 1974. Variation in weight ofcage reared channel catfish. Prog. Fish-Cult. 36:138-144.LEWIS, W. M. 1969. Progress report on the feasibility of feedingchannel catfish incages. Farm Pond Harvest. 3:4-9.NEWTON, S.H. and A.J. MERKOWSKY. 1976. Using light to at-tract insects forcaged catfish. Ark.Farm Res. J. 25:8.NEWTON, S. H.and J.C. DEAN1978. Evaluation of two rations fedto caged channel catfish. Ark.Farm Res. J. 27:6.NEWTON, S. H., W. R. ROBISON and C. J. HASKINS. 1980. Eval-uation ofa full-fatsoybean ration for channel catfish productionin cages. Ark.Acad. of Sci. 34:84-85.NEWTON, S. H. 1980. Status of cage culture in Arkansas. Aquacul-ture magazine. 7:32-36.SCHMITTOU,H. R.1969. The culture of channel catfish, Ictaluruspunctatus (Rafinesque), incages suspended inponds. Proc. S. I-.Assoc. Game and Fish Comm. 23:226-244.'Published withthe appro val ofthe Director ofthe Arkansas Agriculture Experiment Station.SCOTT H.NEWTON and WALTERR. ROBISON, Department ofAgriculture, University ofArkansas at Pine Bluff, Pine Bluff,Arkansas 71601ECONOMICS OF RAINBOW TROUT PRODUCTION INARKANSAS'The major area of rainbow trout (Salmo gairdneri) production inArkansas is the northwest section of the state. This region is noted for itskarst topography with associated underground rivers and springs having ideal water supplies and temperatures for trout production. With in-creased trout usage for both recreational purposes and personal consumption, northwest Arkansas trout producers presently cannot meetdemands. Bycontrast, the delta areas ofArkansas have copious amounts of shallow, easily obtainable water and readily available production sitesthat are being used seasonally for producing farm raised channel catfish (Ictalurus punctatus). Collins (1972) and Newton et al. (1977) reportedthat trout may be reared incages and ponds insouthern Arkansas when water temperatures remain below 21° C. This condition occurs season-ally,usually November through April.The objectives of this study were to further refine pond production methods and to consider the economic potentials of winter trout rearinginthe southern portion of the state.Fish averaging 119 g each were obtained from a northwest Arkansas commercial producer inNovember, 1979. Fish were conditioned fromraceways to ponds and cages for three weeks before commencing the study. One portion of the experiment consisted ofstocking 150 trout ineachof three 0.9 cubic meter cages anchored ina 1.6 ha stock pond. The second part consisted of stocking two 0. 1ha ponds each with 500 fish. Bothtrials were conducted simultaneously at the University ofArkansas at Pine Bluff Research Station from 18 November 1979 through 1 April1980.Allfish were fed a 36% protein commercial floating trout ration. Caged fish were fed five days a week, while pond fish were fed every day.The caged fish were fed on fewer days than the pond fish because they were set up ona different feeding schedule from the pond fish. Feedingrates were adjusted according to water temperature (Klontz, 1978) and were calculated as a percentage of body weight which was estimated bi-monthly (based on an assumed growthrate of 1.7:1 feed conversion efficiency (FCE) or 3.74 kg of food fed for1 kgof fish produced).The average total weight harvested per cage was 29.05 kg, a total net gain of 10.64 kg over average initial stocking weight (Table 1). Survivalaveraged 89% for the caged trout. Fish increased from an average individual size of 122 g to 216 g each during the period, fora 79% average gain.This was similar to growth rates obtained inprevious studies in Arkansas (Collins, 1972; Newton et al., 1977). Food conversion efficiency was1.75:1,higher than that of the previous studies.The harvest weight of pond-reared trout was 121.36 kg (1213.6 kg/ha), a net gain of 53.8 kg over initialstocking weight (Table 2). Troutsurvival in ponds averaged 99.5%, which was also similar to that reported earlier by Newton et al. (1977) but higher than survival reported byKilambiet al. (1977) and Collins (1972). Individual trout increased from 136 g to an average of 245 gin the ponds. The FCE of trout produced inponds was 1.65:1. There was a noted difference among fish from the twoponds inboth total net production and FCE. These differences may bepartially explained by variation in water quality between ponds. During the entire period, fish were observed actively feeding in one pond, whileonlysporadically inthe other pond.Water temperature during the study period averaged 10° C and ranged from 3.8 C-15.4 C(Fig. 1).Klontz (1978) noted that food conversionefficiency and activity of trout were favorable until water temperature dropped below 10° C. He reported an optimum temperature level of14.4°C for trout feed consumption. Growth of trout slowed below 8° Cand ceased below 5.6° C. During our study, conditions for growth were favor-able 75% of the study period and were best for trout production 40% of the time. November, December, March, and Aprilwere the best monthsfor trout production.Winter culture of trout appears quite economically promising. Cages stocked with 150 fish yielded a net profit of $17.10 per cage. Profitwouldbe slightly lower iflabor costs were subtracted. Expenses per cage for the growing season were: feed $10.20 ($O.55/kg) and $49.50 forfingerlings ($0.33 ea). Liveweight wholesale price was $2.64 per kg.Iftrout were marketed on aretail market as opposed to wholesale ($4.07/kg).a net profit of$56.70 per cage wouldbe reasonable. Kilambi et al.(1977) found that a stocking rate of 300 fish per cubic meter didnot significantlylimitgrowth ofcaged trout.Pond-reared trout, at a stocking rate of 5000 per hectare and a harvest weight of 1169 kg, would net $433.96 per hectare based upon a live-weightsellingprice of $2.64 a kilogram. Expenses (per hectare) were: feed cost $1061.61 ($O.55/kg), and fingerling cost of $1590.60 ($0.33 ea).Profit margins may be increased byhigher stocking rates. Jenson (1979) found that a stocking density of 8650 fish per hectare was not limitingtogrowthof trout in Alabama ponds.Trout reared along withcatfish inponds during winter, as reported by Reagan and Robinette (1975) and Newton et al. (1977), had a netreturn on a per hectare per year basis which was higher because the two fish crops could be harvested yearly. Polyculture of trout and catfish alsois feasible because nearly 90% of the trout can be captured with onlyone seine haul without harvesting the catfish. This combination reduces the90Journal of the Arkansas Academy of Science, Vol. 35 [1981], Art. 28https://scholarworks.uark.edu/jaas/vol35/iss1/28

Ration/Density Comparisons with Caged Channel Catfish

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Journal of the Arkansas Academy of ScienceVolume 35 Article 281981Ration/Density Comparisons with CagedChannel CatfishScott H. NewtonUniversity of Arkansas at Pine BluffWalter R. RobisonUniversity of Arkansas at Pine BluffFollow this and additional works at: http://scholarworks.uark.edu/jaasPart of the Aquaculture and Fisheries CommonsThis article is available for use under the Creative Commons license: Attribution-NoDerivatives 4.0 International (CC BY-ND 4.0). Users are able toread, download, copy, print, distribute, search, link to the full texts of these articles, or use them for any other lawful purpose, without asking priorpermission from the publisher or the author.This General Note is brought to you for free and open access by ScholarWorks@UARK. It has been accepted for inclusion in Journal of the ArkansasAcademy of Science by an authorized editor of ScholarWorks@UARK. For more information, please contact scholar@uark.edu, ccmiddle@uark.edu.Recommended CitationNewton, Scott H. and Robison, Walter R. (1981) "Ration/Density Comparisons with Caged Channel Catfish," Journal of the ArkansasAcademy of Science: Vol. 35 , Article 28.Available at: http://scholarworks.uark.edu/jaas/vol35/iss1/28Arkansas Academy of Science Proceedings, Vol.XXXV,1981 89General NotesMOORE, D.M. 1953. Rediscovery ofbigleaf magnolia in Arkansas.Abstract. Proc. Ark.Acad. Sci. 6:9.SPEAIRS, R. K.,JR. 1976. Ouachita biological station. Proc. Ark.Acad. Sci. 30:83.SMITH,E. B. 1978. Atlas and annotated list of the vascular plants ofArkansas. Univ.Ark.Fayetteville.JEWEL E. MOORE, Department ofBiology, University ofCentral Arkansas, Conway, Arkansas 72032, and INEZHARTSOE (retired), PiggottHigh School, Piggott, Arkansas 72454.RATION/DENSITY COMPARISONS WITH CAGED CHANNEL CATFISH*Caged fish culture as a production method for rearing catfish and trout was first started inthe United States in the late 1%0's and has nowbecome more practical than ever for certain situations (Newton, 1980). This is especially true for the utilization of farm ponds whichare suitablefor cages because the fish cannot be easily harvested otherwise. Since 1967, university and governmental researchers have studied and developedcaged catfish culture for the fish farming industry (Lewis, 1969; Schmittou, 1969; Collins, 1971). They first dealt withculture techniques involvingpotentials and adaptations of the method. They used numerous types ofcages and gradually refined studies to include nutritional trials, stockingsizes and rates, genetics, and fish health (Collins, 1978).Research conducted during the 1970's, primarily in Arkansas and Oklahoma, has further refined cage culture methodology and applicationpotentials (Collins, 1971; Collins, 1978; Newton, 1980; Kilambi et al., 1977). These studies are valuable because they demonstrate the variety ofsituations for using cage culture, the improved feed quality for confined fish culture, and the resource potential for both home and commercialventures.Cages are ideal forevaluating rations for fishdiets (Newton and Dean, 1978; Newton et al., 1980). The need continues for testing availablerations forefficient and economical fish production. This study compares two rations ofsimilar protein levels, 33% and 36%, but quite differentin cost withthree stocking densities ofchannel catfish.A total of 18 cages were stocked withcatfish fingerlings during May 1980. Thecages (0.9m1) were arranged inunits of three across the southend of a 1.6 ha farm pond on the University of Arkansas at Pine BluffAgricultural Research Station as described previously by Newton andMerkowsky (1976). Six cages were each stocked with 200, 350, and 500 fingerlings (average wt. 28 g), respectively, in a randomized pattern.Experimental conditions were triplicated simultaneously for ration and density evaluations. Three cages of each fish density were fed either a36% protein trout ration or a 33% protein catfish ration formulated as floating pellets. Allfish were fed fivedays per week at the rate of4% oftheir estimated body weight, regardless ofdensity or ration combinations.The study period began 14 May and ended on 30 August due to an oxygen depletion whichkilled fish in approximately two-thirds of thecages. Nevertheless, all data were collected from each cage similar tousual harvest operations inprevious studies (Newton et al., 1980). Statisticalcomparisons revealed nosignificant differences between data collected from dead or live fish. Therefore, the relative validity of the assumptionsand determinations reported herein are believed tobe accurate forpractical comparisons among density and ration combinations.Evaluations of the rations and stocking densities were based upon weight gain, food conversion efficiency (FCE), survival, and productioncosts per kilogram of catfish produced. Comparisons between rations revealed no significant differences among net production, FCE, andsurvival. Due to the difference in feed costs (the 33% protein ration was $16/45.5 kg, while the 36% protein ration was $25/45.5 kg) the 33%protein ration was the most cost efficient at allstocking densities (Table 1). With either ration, the cost per kilogram of fish produced was less atthe higher stocking densities (350 and 500 fish); however, production costs were still lower for all densities with the 33% protein catfish ration.The greatest net profit per cage was obtained withthe highest fish density forboth rations.There were significant differences in net production among each stocking density, although survival and FCE were similar (Table 2). Fishstocked at 350 per cage had higher average individual gains than fish stocked at 200 or 500 per cage, whichhad similar average gains. Both FCEand survival were consistently within normal ranges necessary for successful caged catfish production. Survival was unusually high, until theoccurrence of the oxygen depletion. One of the disadvantages of cage culture is that caged fish are more susceptible to oxygen problems than fishinan open pond.Since the fish stocked at 350 per cage had higher individual gains with both rations, it appears that this stocking density was optimum forproducing larger size fish. Fish density considerations have been studied forsome time (Schmittou, 1969; Konikoffand Lewis, 1974), and it hasbeen determined that generally a minimum number of 5-6 fish per 30 cm5 isrequired to avoid behavioral problems. We have used 7-8 fish inmostofour studies; however, the maximum or optimum number to stock deserves further attention. Ahigh quality, less expensive catfish ration out-performed a more expensive trout ration on the basis of fishproduction, economy, and availability.This study was supported withfunds provided by USDA,SEA/CR under PL 95-113.89Journal of the Arkansas Academy of Science, Vol. 35 [1981], Art. 28Published by Arkansas Academy of Science, 198190 Arkansas Academy of Science Proceedings, Vol.XXXV,1981LITERATURE CITEDCOLLINS, C. M. 1978. Catfish cage culture, fingerlings to food fish.Kerr Foundation, Inc.Poteau, OK.22pp.COLLINS, R.A. 1971. Cage culture of catfish in reservoir lakes.Proc. S. E. Assoc. Game and Fish Comra. 24:489-4%.KILAMBI,R. V.,J. ADAMS,A.V. BROWN and W. WICKIZER.1977. Effects of stocking density and cage size on growth, feedconversion, and production of rainbow trout and channel catfish.Prog. Fish-Cult. 39:62-66.KONIKOFF, M. and W. M. LEWIS 1974. Variation in weight ofcage reared channel catfish. Prog. Fish-Cult. 36:138-144.LEWIS, W. M. 1969. Progress report on the feasibility of feedingchannel catfish incages. Farm Pond Harvest. 3:4-9.NEWTON, S.H. and A.J. MERKOWSKY. 1976. Using light to at-tract insects forcaged catfish. Ark.Farm Res. J. 25:8.NEWTON, S. H.and J.C. DEAN1978. Evaluation of two rations fedto caged channel catfish. Ark.Farm Res. J. 27:6.NEWTON, S. H., W. R. ROBISON and C. J. HASKINS. 1980. Eval-uation ofa full-fatsoybean ration for channel catfish productionin cages. Ark.Acad. of Sci. 34:84-85.NEWTON, S. H. 1980. Status of cage culture in Arkansas. Aquacul-ture magazine. 7:32-36.SCHMITTOU,H. R.1969. The culture of channel catfish, Ictaluruspunctatus (Rafinesque), incages suspended inponds. Proc. S. I-.Assoc. Game and Fish Comm. 23:226-244.'Published withthe appro val ofthe Director ofthe Arkansas Agriculture Experiment Station.SCOTT H.NEWTON and WALTERR. ROBISON, Department ofAgriculture, University ofArkansas at Pine Bluff, Pine Bluff,Arkansas 71601ECONOMICS OF RAINBOW TROUT PRODUCTION INARKANSAS'The major area of rainbow trout (Salmo gairdneri) production inArkansas is the northwest section of the state. This region is noted for itskarst topography with associated underground rivers and springs having ideal water supplies and temperatures for trout production. With in-creased trout usage for both recreational purposes and personal consumption, northwest Arkansas trout producers presently cannot meetdemands. Bycontrast, the delta areas ofArkansas have copious amounts of shallow, easily obtainable water and readily available production sitesthat are being used seasonally for producing farm raised channel catfish (Ictalurus punctatus). Collins (1972) and Newton et al. (1977) reportedthat trout may be reared incages and ponds insouthern Arkansas when water temperatures remain below 21° C. This condition occurs season-ally,usually November through April.The objectives of this study were to further refine pond production methods and to consider the economic potentials of winter trout rearinginthe southern portion of the state.Fish averaging 119 g each were obtained from a northwest Arkansas commercial producer inNovember, 1979. Fish were conditioned fromraceways to ponds and cages for three weeks before commencing the study. One portion of the experiment consisted ofstocking 150 trout ineachof three 0.9 cubic meter cages anchored ina 1.6 ha stock pond. The second part consisted of stocking two 0. 1ha ponds each with 500 fish. Bothtrials were conducted simultaneously at the University ofArkansas at Pine Bluff Research Station from 18 November 1979 through 1 April1980.Allfish were fed a 36% protein commercial floating trout ration. Caged fish were fed five days a week, while pond fish were fed every day.The caged fish were fed on fewer days than the pond fish because they were set up ona different feeding schedule from the pond fish. Feedingrates were adjusted according to water temperature (Klontz, 1978) and were calculated as a percentage of body weight which was estimated bi-monthly (based on an assumed growthrate of 1.7:1 feed conversion efficiency (FCE) or 3.74 kg of food fed for1 kgof fish produced).The average total weight harvested per cage was 29.05 kg, a total net gain of 10.64 kg over average initial stocking weight (Table 1). Survivalaveraged 89% for the caged trout. Fish increased from an average individual size of 122 g to 216 g each during the period, fora 79% average gain.This was similar to growth rates obtained inprevious studies in Arkansas (Collins, 1972; Newton et al., 1977). Food conversion efficiency was1.75:1,higher than that of the previous studies.The harvest weight of pond-reared trout was 121.36 kg (1213.6 kg/ha), a net gain of 53.8 kg over initialstocking weight (Table 2). Troutsurvival in ponds averaged 99.5%, which was also similar to that reported earlier by Newton et al. (1977) but higher than survival reported byKilambiet al. (1977) and Collins (1972). Individual trout increased from 136 g to an average of 245 gin the ponds. The FCE of trout produced inponds was 1.65:1. There was a noted difference among fish from the twoponds inboth total net production and FCE. These differences may bepartially explained by variation in water quality between ponds. During the entire period, fish were observed actively feeding in one pond, whileonlysporadically inthe other pond.Water temperature during the study period averaged 10° C and ranged from 3.8 C-15.4 C(Fig. 1).Klontz (1978) noted that food conversionefficiency and activity of trout were favorable until water temperature dropped below 10° C. He reported an optimum temperature level of14.4°C for trout feed consumption. Growth of trout slowed below 8° Cand ceased below 5.6° C. During our study, conditions for growth were favor-able 75% of the study period and were best for trout production 40% of the time. November, December, March, and Aprilwere the best monthsfor trout production.Winter culture of trout appears quite economically promising. Cages stocked with 150 fish yielded a net profit of $17.10 per cage. Profitwouldbe slightly lower iflabor costs were subtracted. Expenses per cage for the growing season were: feed $10.20 ($O.55/kg) and $49.50 forfingerlings ($0.33 ea). Liveweight wholesale price was $2.64 per kg.Iftrout were marketed on aretail market as opposed to wholesale ($4.07/kg).a net profit of$56.70 per cage wouldbe reasonable. Kilambi et al.(1977) found that a stocking rate of 300 fish per cubic meter didnot significantlylimitgrowth ofcaged trout.Pond-reared trout, at a stocking rate of 5000 per hectare and a harvest weight of 1169 kg, would net $433.96 per hectare based upon a live-weightsellingprice of $2.64 a kilogram. Expenses (per hectare) were: feed cost $1061.61 ($O.55/kg), and fingerling cost of $1590.60 ($0.33 ea).Profit margins may be increased byhigher stocking rates. Jenson (1979) found that a stocking density of 8650 fish per hectare was not limitingtogrowthof trout in Alabama ponds.Trout reared along withcatfish inponds during winter, as reported by Reagan and Robinette (1975) and Newton et al. (1977), had a netreturn on a per hectare per year basis which was higher because the two fish crops could be harvested yearly. Polyculture of trout and catfish alsois feasible because nearly 90% of the trout can be captured with onlyone seine haul without harvesting the catfish. This combination reduces the90Journal of the Arkansas Academy of Science, Vol. 35 [1981], Art. 28http://scholarworks.uark.edu/jaas/vol35/iss1/28

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Ration/Density Comparisons with Caged Channel Catfish

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