Effects of three dietary protein levels on the growth of pacu, Colossoma mitrei Berg, in cages

Abstract. Artificially reproduced pacu, Colossoma mitrei Berg, fingerlings (initial weight 41 g) were stocked (100/m³) in plastic cages (1·0m³) within a freshwater reservoir. Three diets containing 30, 35 and 40% protein were tested in quadruplicate over a 76-day experimental feeding period. Fish were fed 7 days a week, twice daily at a feeding regime of 4% body weight/day from stock to 100g and thereafter at 3% until harvest. Mean water temperature over the trial was 26·7°C. Significant differences were observed in total and daily gain and in protein efficiency ratio, while no differences were obtained in the feed conversion ratio between treatments. Based on this study a 35% protein ration is recommended for pacu within floating cages.     

Effect of dietary protein, lipid and carbohydrate ratio on growth, feed efficiency and body composition of pikeperch Sander lucioperca fingerlings

Pikeperch Sander lucioperca fingerlings were fed nine practical diets containing three levels of protein (P=34%, 43% and 50%), lipid (L=10%, 16% and 22%) and carbohydrate (C=10%, 15% and 20%) for 10 weeks in a recirculating water system at 23°C. Dietary treatments were distributed by orthogonal design with dietary energy content ranging from 15.5 to 23.1 MJ kg^?1 diet. Significant differences (P<0.05) in weight gain (%) and feed efficiency (FE) were observed after feeding trial. Relatively low growth and FE were found in fish fed diets containing 34% dietary protein level compared with that of fish fed diets with 43–50% protein levels, suggesting that 34% dietary protein probably is below the protein requirements of pikeperch fingerlings. Fish fed diets containing P43L10C15, P43L22C20 and P50L16C20 had significantly (P<0.05) higher weight gain and FE than fish fed the diets containing other dietary P/L/C ratios. There was no significant difference in weight gain and FE between fish fed diets of P43L10C15, P43L22C20 and P50L16C20. These results may indicate that pikeperch require at least 43% of dietary protein for adequate growth and FE, and considering the fish growth and feed ingredient cost P43L10C15 diet is more cost‐effective formulation for pikeperch fingerling. However, protein efficiency was not significantly affected by dietary P/L/C ratio.     

Optimum feeding rate, and energy and protein maintenance requirements of young Clarias batrachus (L.), a cultivable catfish species

Abstract. Protein and energy maintenance and optimum feed requirements are reported in the catfish, Clarias batrachus (L.), fed a purified diet (40% CP; 1487·1kJ/100g) at 0 to 8% (BW/day) ration levels. Linear (r = 0·985) increase was observed in daily average growth increment up to a ration level of 4% (BW/day), corresponding to 6·03g protein/(kg^0·8BW/day) and 224·26 kJ energy/(kg^0·8 BW/day). Maintenance requirements, obtained by regressing daily average growth increment to zero, were 0·942 g/(kg^0·8 BW/day) for protein and 36·02 kJ/(kg^0·8BW/day) for energy. Net gains in muscle protein and energy also depicted linear increase (r = 0·975) with feeding levels up to 6·03g protein/(kg^0·8 BW/day) and 224·26kJ energy/(kg^0·8 BW/day). On fitting the above data to regression equations, giving the amount of dietary protein and energy required to maintain a constant amount of body protein and energy, values of 1·005g/(kg^0·8 BW/day) and 42·11 kJ/(kg^0·8BW/day) were obtained for protein and energy respectively. The optimum feeding rate for this species, as evident from specific growth rate and conversion efficiencies, appears to be 3% (BW/day) at 30 ± 2°C. Moisture and lipid contents in muscle were found to be significantly ( P < 0·05) affected by the ration levels.     

Effect of dietary protein levels on growth,feed utilization and carcass composition of endangered bagrid catfish Horabagrus brachysoma (Gunther 1864) fingerlings

An 84‐day feeding trial was conducted to study the effect of different levels of dietary protein, 250 (P25), 300 (P30), 350 (P35), 400 (P40) and 450 g (P45) kg^?1 dry matter (DM) on growth, feed intake, feed utilization and carcass composition of bagrid catfish Horabagrus brachysoma fingerlings. Triplicate groups of fingerlings with mean initial body weight of 2.2 g were fed the experimental diets twice daily, till satiation, in 150‐L tanks supplied with flow‐through freshwater. Daily dry matter intake by the fingerlings decreased significantly (P < 0.05) when fed P25 diet, containing 250 g protein kg^?1. The highest body weight gain, specific growth rate (SGR) and protein efficiency ratio (PER), and the lowest feed conversion ratio (FCR) were observed in fish fed 350 g protein kg^?1 diet. The fish fed with P45 diet had the lowest (P < 0.05) carcass lipid content. The polynomial regression analysis indicates that H. brachysoma fingerlings require 391 g dietary crude protein kg^?1 diet.     

Effects of Dietary Fiber on Growth and Gastric Emptying Time of the Freshwater Prawn Macrobrachiurn rosenbergii (De Man, 1879)

Feeding experiments were conducted on large and small adult freshwater prawns Macrobrachium rosenbergii (36.96 ± 1.65 and 13.48 ± 1.65 g in weight) to determine the impact of dietary fiber on growth, digestion, and gastric emptying time. Fiber was incorporated as Q- cellulose into four semi-purified diets at calculated levels of 0, 5, 10 and 15% at the expense of starch and fed for an 8-wk period. The experiment was conducted in a closed, filtered, recirculating freshwater system. The results indicate that the specific growth rates, feed conversion ratios, and protein efficiency ratios improved as the levels of dietary fiber increased from 0.4% to 8%. Gastric emptying times increased as the level of inclusion of cellulose in the diets increased. It was concluded that diets containing up to 10% dietary fiber increases growth rates in adult prawn Macrobrachium rosenbergii by increasing nutrient residence time in the gastrointestinal tract, thereby increasing absorption.     

Growth and efficiency of feed usage by Atlantic salmon (Salmo salar) fed diets with different dietary protein: Energy ratios at two feeding levels

The effect of dietary digestible protein/digestible energy (DP/DE) ratios and feeding level on growth, feed efficiency, nutrient and energy usage by Atlantic salmon ( Salmo salar ; initial body weight, 7.0 g/fish) at 15°C was investigated in a 16-week feeding trial. Three diets, differing in their DP and DE contents, namely 37/18 (regular diet, RD), 37/21 (high fat diet, HF) and 44/ 22 (high nutrient-dense diet, HND) g/MJ of dry feed were formulated. DP/DE ratios were 20, 18 and 20 g/MJ for the RD, HF and HND diets, respectively. Salmon were hand-fed three times a day at either 100% or 85% of the feed requirement estimated by a bioenergetics model. At each feeding level, DE intake (kJ/fish) was similar for all three diets. Diet composition did not affect growth rate. However, increasing the digestible energy density from 18 to 22 MJ/kg of dry feed resulted in a significant increase ( P  < 0.05) in feed efficiency. Restricting feed intake significantly decreased live body weight gains for all diets. However, feed efficiency was not affected by feeding level. Diet composition and feeding level did not affect carcass composition and nutrient and energy usage, with the exception of a higher ( P  < 0.05) carcass lipid of fish fed the HF100 diet compared with the fish fed the RD and HND diets and a higher ( P  < 0.05) lipid gain (g/fish) of fish fed the HF100 diet compared with fish fed all the diets at the restricted feeding level. Restricting feeding resulted in significantly lower ( P  < 0.05) energy gain (kJ/fish) compared with fish fed at 100%. Increasing the DE and nutrient density of the diet had no effect on growth but improved feed efficiency and lowered solid wastes (g of solid wastes per kg of fish produced) while dissolved wastes were not affected by dietary ormulation.     

The effect of dietary lipid and lecithin levels on the growth, survival, feeding efficiency, production and carcass composition of post-larval Penaeus monodon Fabricius

Abstract. Eight semi-purified diets were formulated to investigate the effects of dietary lipid and lecithin levels on the performance and carcass composition of post-larval Penaeus monodon Fabricius.
Supplementary soyabean lecithin levels from 0 to 9% and total dietary lipid (cod liver oil:soyabean oil at a ratio of 3:1) levels from 3·5 to 12·5% at 3% increments were tested in diets that were isonitrogenous and isoenergetic. The diets were fed for 50 days to triplicate groups of post-larval P. monodon held in a laboratory marine recirculated water system.
Despite poor overall performance due to the purified dietary ingredients, the absence of basal lipids and/or lecithin was found to result in the poorest performance. Optimum production was obtained with a diet containing 3% basal lipid and 3% lecithin at a total lipid level of 6·5%. The addition of dietary lecithin (particulariy at 46·63% of the total lipid) at up to 3% in terms of growth, feeding efficiency and production or 6% in terms of survival significantly ( P < 0·05) increased shrimp production. Lecithin was therefore probably acting as a growth, survival and/or phago-stimulant in P. monodon.
The total lipid requirements are consistent with those reported by other workers for penaeid shrimp, and are probably a result of the requirement for essential fatty acids, the stimulant properties of lecithin and the calorigenic effects of high dietary lipid levels.     

Evaluation of Semipurified Test Diets for Tilapia zillii Fingerlings

An experiment was conducted to evaluate semipurified test diets for Tilapia zillii fingerlings. Four isocaloric (300 kcal dietary energy/100 g) diets containing casein (at 30 and 39%). casein supplemented with L-arginine (Arg) and casein/gelatin mixture as protein sources were fed to triplicate groups of T. zillii fingerlings at a daily rate of 3% of their body weight for 6 weeks. When casein was fed as the sole dietary protein source at 30% level, fish growth, feed conversion efficiency (FC) and protein efficiency ratio (PER) were significantly reduced. Those variables were significantly improved when casein was supplemented with Arg. The group of fish fed casein/gelatin diet showed the best growth and feed utilization. When casein was increased to 39% to meet the Arg requirement, fish growth and feed conversion were not significantly different from those of fish fed casein/gelatin diet, while PER and protein production value (PPV) were significantly reduced. These results indicated that casein/gelatin is superior to casein or casein/Arg as a protein source in semipurified test diets for T. zillii fingerlings.     

Supplemental effect of <Emphasis Type="Italic">Porphyra</Emphasis> spheroplasts on the growth and feed utilization of black sea bream

ABSTRACT:   A 56-day feeding trial was conducted to evaluate the effects of Porphyra spheroplasts (PS) as a feed additive on growth, carcass composition and feed utilization of black sea bream. Four experimental diets with or without PS (0, 1, 3, 5% inclusion level) were formulated to determine the proper incorporation level for best growth and utilization using white fishmeal as the principal protein source. Three replicate groups of fish averaging 1.28 ± 0.05 g (mean ± SD) were maintained in flow-through thermo-controlled sea water (32–34 psu, 25°C) aquaria (100 L) under the laboratory conditions (L12 : D12) and fed three times a day at 09:00, 13:00 and 17:00 hours by hand at approximately 3% body weight on each diet. The rearing trial revealed that growth performance (in terms of weight gain, specific growth rate) are almost the same level in all the dietary groups, nevertheless the survival, nutrient utilizations and retentions (feed efficiency, protein efficiency ratio, protein retention rate, lipid retention rate) were significantly higher ( P  < 0.05) in a group fed on the diet containing 3% spheroplasts. Further, the fish fed on the diet containing PS had significantly higher ( P  < 0.05) crude lipid level in their dorsal muscles and viscera. The fish fed a PS-based diet showed higher level of eicosapentaenoic acid and docosahexaenoic acid (DHA) in viscera and DHA in dorsal muscles. The results obtained in this feeding trial suggest that the optimum dietary PS supplementation level up to 3% for black sea bream can be considered as improved consequence on growth performance, nutrient utilization or body composition were noticed.     

Optimal dietary lipid level of silver barb, Puntius gonionotus fingerlings in relation to growth, nutrient retention and digestibility, muscle nucleic acid content and digestive enzyme activity

Five iso-nitrogenous (300 g kg⁻¹ diet) purified diets with graded level of lipid at 40 (D-1), 60 (D-2), 80 (D-3), 100 (D-4) and 120 (D-5) g kg⁻¹ diet were fed to Puntius gonionotus fingerlings for 90 days to determine their dietary lipid requirement. Two hundred and twenty-five fingerlings (average weight 2.34 ± 0.03 g) were equally distributed in five treatments in triplicate groups with 15 fish per replicate. Fifteen flow-through cement tanks of 100 L capacity with a flow rate of 0.5 L min⁻¹ were used for rearing the fish. Specific growth rate (SGR), feed conversion ratio (FCR), nutrient digestibility, retention, digestive enzyme activity, RNA : DNA ratio and whole-body composition were considered as the response parameters with respect to dietary lipid levels. Maximum SGR and minimum FCR with highest RNA : DNA ratio, whole-body protein content and digestive enzyme activity was found in D-3 group fed with 80 g kg⁻¹ diet lipid. Nutrient digestibility was similar in all the groups irrespective of the dietary lipid level. Maximum protein and energy retention was recorded at 80 g kg⁻¹ dietary lipid fed group. However, from the second-order polynomial regression analysis, the maximum growth of P. gonionotus fingerlings was found at 96.9 g lipid kg⁻¹ diet.     

Effect of stocking density on growth and survival of Oreochromis niloticus (L.) fry in the hatchery

Abstract. The effect of stocking density on growth and survival of Oreochromis niloticus (L.) fry was evaluated. O. niloticus fry (average weight, 10·56 ± 0·28mg and average length. 9·09 ± 0·05nim) were stocked in 2–1 tanks at 2, 5, 10, 15 and 20 fry/1 and reared for 33 days post fertilization, at 30°C (±1°C). Mean lengths, mean weights, and specific growth rates were found to be significantly lower ( P < 0·05) at the higher stocking densities. The coefficient of variation for the five stocking densities was significantly ( P < 0·05) different. Condition factors, however, were not significantly ( P < 0·05) different and survival was high at all density treatments. These data suggest that the culture of O. niloticus is feasible at the density groups tested but 5–10fry/I is recommended for fry culture in the hatchery, if a more uniform size is desired.     

Microbial Phytase Supplementation in Rohu, Labeo rohita, Diets Enhances Growth Performance and Nutrient Digestibility

Abstract.— A feeding trial was conducted for 60 d to study the effect of dietary microbial phytase on growth performance and nutrient digestibility of rohu, Labeo rohita , fingerlings. One hundred and twenty fingerlings (average initial weight: 9.17 g/fish) were equally distributed into five experimental tanks, each with four replicates. Five isonitrogenous (35%) and isocaloric (16.79 kJ/g) diets were prepared from plant-based ingredients, supplemented with microbial phytase at the level of 0, 250, 500, 750, and 1000 U/kg diets and fed to T₀, T₁, T₂, T₃, and T₄ groups, respectively. Weight gain %, food conversion ratio, protein efficiency ratio, and apparent net protein utilization were significantly ( P  < 0.05) improved in groups fed phytase-supplemented diets compared to control, the highest being observed in T₃ group. Maximum apparent digestibility of phosphorus and crude protein was recorded in T₃ group. Bone ash, phosphorus (P), and calcium (Ca) contents were also significantly ( P  < 0.05) increased in phytase-fed groups. However, maximum was recorded in T₃ group. Results from the present study indicated that addition of 750 U microbial phytase/kg diets effectively improved nutrient utilization, bone mineralization, and hence growth of L. rohita fingerlings.     

Effects of dietary lipid and reduced glutathione on composition and storage quality of channel catfish, Ictalurus punctatus (Rafinesque)

Abstract. Semi-purified casein/gelatin diets containing two levels of lipid (5 or 10%) and three levels of reduced glutathione (0,0·1 or 1·0%) in a factorial arrangement were fed to fingerling channel catfish, Ictalurus punctatus (Rafinesque), in aquaria for 10 weeks. Factorial analysis of variance indicated that dietary lipid had significant ( P < 0·05) effects on growth, feed efficiency and body composition of channel catfish. Diets containing 10% lipid generally produced higher weight gain and feed efficiency values as well as higher intraperitoneal fat. The higher level of dietary lipid also produced lower moisture and higher lipid (on a wet-weight basis) levels in whole-body and fillet tissues. Stability of fillet samples was estimated by 2-thiobarbituric acid (TBA) analysis which revealed that 10% dietary lipid significantly elevated fillet TBA values while glutathione did not have any effect. Therefore, dietary lipid level altered growth and body composition of channel catfish as well as oxidative stability of fillet samples while dietary glutathione was generally ineffective.     

Evaluation of heat-processed cocoa pod husk meal as an energy feedstuff in production diets for the clariid catfish, Clarias isheriensis (Sydenham)

Isoproteic and isoenergetic diets containing 0%, 15%, 30% or 45% heat-processed cocoa pod husk meal (CPHM) were fed to Clarias isheriensis (16.8 ± 2.4 g) for 180 days. Growth rates of catfish fed varying levels of CPHM were similar (P > 0.05). Differences in feed-gain ratio (FGR) or protein efficiency ratio (PER) between treatments were not significant (P > 0.05). Histology of the liver showed no pathological effects of incorporation of CPHM. In a second experiment, C. isheriensis (19.1 ± 3.5 g) were fed isoenergetic diets containing 250, 300, 350 and 400 protein g kg^?1 (protein: energy ratios of 21, 25, 29 and 33 mg protein.kJ^?1 DE, respectively). Growth rate and FGR improved (P < 0.05) in proportion to the dietary protein level. PER decreased with increase in dietary protein. Carcass protein was lowest (P < 0.05) in catfish fed 250 g protein kg^?1, but did not differ among the other diets (P > 0.05). Body fat was highest in catfish fed 250 g protein kg^?1 and lowest in fish fed 350 g protein kg^?1. These results indicate that CPHM may be a suitable carbohydrate energy source for clariids at a P:E ratio of approximately 29 mg protein.kJ^?1 DE.     

Effects of Dietary Chlorella ellipsoidea Supplementation on Growth, Blood Characteristics, and Whole-Body Composition in Juvenile Japanese Flounder Paralichthys olivaceus

The study was conducted to investigate the effects of dietary Chlorella powder (C) supplementation on growth performance, blood characteristics, and whole-body composition in juvenile Japanese flounder Paralichthys olivaceus . Four experimental diets were supplemented with C at 0, 1, 2 and 4% (C₀, C₁, C₂, and C₄) on a dry-weight basis. Three replicate groups of fish averaging 1.13 ± 0.02 g (Mean ± SD) were randomly distributed in each aquarium and fed one of four experimental diets for 12 wk. After 12 wk of the feeding trial, fish fed C₂ diet had higher weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) than did fish fed C₀ and C₁ diets ( P 0.05); however, there was no significant difference among fish fed C₁ and C₄ diets, and among fish fed C₂ and C₄ diets ( P > 0.05). Fish fed C₂ and C₄ diets had a lower serum cholesterol level than did fish fed C₀ and C₁ diets ( P 0.05). Fish fed C₂ and C₄ diets had a lower body fat than did fish fed C₀ ( P 0.05). These results indicate that dietary supplementation of 2% Chlorella powder in the commercial diets could improve growth, feed utilization, serum cholesterol level, and whole-body fat contents in juvenile Japanese flounder.     

Effect of dietary lysine and methionine supplementation on growth, nutrient utilization, carcass compositions and haemato-biochemical status in Indian Major Carp, Rohu (Labeo rohita H.) fed soy protein-based diet

An 8-week feeding trial was conducted in flow through system to examine the effects of dietary supplementation of lysine and methionine on growth, nutrient utilization, haemato-biochemical status and carcass compositions in Indian major carp, rohu, Labeo rohita fingerlings (average weight 6.32 ± 0.06 g). Four experimental soy protein-based diets D ₀ (without lysine or methionine supplementation), D ₁ (lysine supplementation alone), D ₂ (methionine supplementation alone) and D₃ (both lysine and methionine supplementation) were fed to triplicate groups. l -Lysine and dl -methionine were added to the diets containing 550 g kg⁻¹ soybean meals at 4 and 7 g kg⁻¹ of dry diet respectively. Significant higher weight gain, specific growth rate (SGR), protein efficiency ratio (PER), dry matter retention, nitrogen retention, total ash retention, whole carcass protein, haemoglobin concentration, haematocrit value, total erythrocytic count, total leucocytic count, plasma glucose and plasma total protein and lower FCR, per cent lipid retention and whole body moisture content were observed in fish fed soya protein-based diet supplemented with both lysine and methionine than that of fish of other dietary groups at the end of 8 weeks feeding trial. Although fish fed diet supplemented with either methionine or lysine did not show any significant differences of growth performances, feed utilization, carcass composition and haemato-biochemical status, fish of both of these dietary groups showed significantly better growth performances, feed utilization, carcass composition and haemato-biochemical status than that of fish fed diet without lysine and methionine supplementation.     

Seasonal production of rainbow trout, Oncorhynchus mykiss (Walbaum), in ponds using different feeding practices

Abstract. In temperate regions of North America, the culture of rainbow trout, Oncorhynchus mykiss (Walbaum), in ponds is constrained to the period mid-November to early April by water temperature. Feeding practice may influence production time. The effects of three feeding practices on growth and body composition of rainbow trout raised in ponds during a 142-day winter growth period were investigated. Feeding practices were (1) hand-feeding to satiation, (2) feeding according to a fish size/water temperature chart, and (3) feeding by demand feeder.
Fish fed to satiation consumed 66% more diet than fish fed according to a feeding chart and 163% more than fish fed by demand feeders. Fish fed to satiation had significantly higher (P < 0·05) weight gain, harvest weight, specific growth rate, and protein gain with no significant increase (P > 0·05) in percentage body fat or feed conversion ratio (FCR) compared to the other two treatments. Survival percentage did not differ significantly (P > 0·05) between treatments. These data indicate that by using satiation feeding, marketable size rainbow trout can be produced in temperate region ponds without increases in percentage body fat or FCR.     

Growth, feed utilization and nutrient digestibility in tilapia fingerlings (Oreochromis aureus Steindachner) fed diets containing bacteria-treated coffee pulp

The effectiveness of bacteria treated‐coffee pulp (BT‐CoP) in fish diets was evaluated in a feeding trial with Oreochromis aureus (Steindachner) fingerlings. Five diets were formulated to contain 0%, 6%, 12%, 18% and 24% BT‐CoP, replacing wheat meal. Fish were reared in a recirculating unit consisting of 16 aquaria. Each aquarium was stocked with 10 fish of 1.1–2.4 g. Fish were fed ad libitum twice daily (10 and 15 h) for 4 weeks. Fish fed diets without BT‐CoP and with 6% BT‐CoP showed similar growth (body weight, growth rate: RGR_m) and feed utilization (feed conversion ratio, protein efficiency ratio, apparent net protein utilization). Diets containing 0% and 6% BT‐CoP gave similar dry matter and protein digestibility coefficients, but dietary BT‐CoP levels higher than 6% produced lower digestibility values, except for carbohydrate. It is concluded that O. aureus fingerlings may assimilate only small amounts (6%) of BT‐CoP in the diets without adverse effects on growth and feed utilization parameters. The CoP‐containing diets did not affect fish survival (100%). The depression in tilapia performance may be associated mainly with the high level of fibre present in the CoP diets.     

Replacement of by-catch fishmeal with dried chicken viscera meal in extruded feeds: effect on growth,nutrient utilisation and carcass composition of catfish <Emphasis Type="Italic">Clarias batrachus</Emphasis> (Linn.) fingerlings

An 84-day feeding trial was conducted to study the effect of replacing dietary fishmeal with dried chicken viscera meal (CVM) on the growth (net biomass gain, specific growth rate, SGR), feed acceptability, feed conversion ratio (FCR), protein efficiency ratio (PER) and carcass composition of Clarias batrachus fingerlings. Triplicate groups of fingerlings with mean initial body weight of 13.35 g were fed on six iso-nitrogenous and iso-lipidic diets. The control diet (CVM0) used marine by-catch fishmeal as the sole source of animal protein. In the other five diets (CVM100–CVM500), 20–100% of fishmeal was substituted by dried CVM at 20% increments. The highest body weight gain, SGR and PER, and the lowest FCR were observed in fish fed a diet containing 300–500 g CVM kg⁻¹. The fish accumulated increasing quantities of lipids and decreasing levels of ash in their carcasses with increasing levels of dietary CVM.     

Replacing dietary corn with barley seeds in Nile tilapia, Oreochromis niloticus (L.), feed

Four isocaloric–isonitrogenous rations containing 0%, 15%, 30% and 51% of ground barley seeds as a replacement for dietary corn were fed to three replicate groups of Oreochromis niloticus (Linnaeus) fingerlings with a mean initial weight of 3.5 g. The randomly selected fish were tested for 9 weeks in 60 L circular tanks. Each tank was considered as an experimental unit. The tanks were put together in a water recirculating system using filtered and aerated ground well water (24 ± 3 °C). Tilapia weight gain, feed conversion, specific growth rate and protein efficiency ratio were similar in fish fed diets containing 15% and 30% barley and were superior to those fed diets containing 0% control and 51% barley. There were no differences between tilapia fed diets containing 0% and 51% barley. Body moisture, crude fat, crude protein and total ash did not change as the level of barley in the feeds was increased.