Evaluation of mixed feeding schedules with respect to compensatory growth and body composition in African catfish Clarias gariepinus

An 8‐week feeding trial was conducted in a recycling water system at 28 ± 1 °C to investigate compensatory growth and body composition in African catfish Clarias gariepinus (13.05 ± 0.05 g). A fishmeal‐based diet containing 350 g kg^?1 protein and 17.5 kJ g^?1 gross energy was fed to triplicate groups of 20 fish (per 30‐L tank). Fish were fed the diet either to satiation or feed restricted in six feeding schedules as satiation 56 days; restricted 28 days + satiation 28 days; restricted 14 days + satiation 14 days; restricted 7 days +satiation 7 days; restricted 3 days + satiation 4 days; and restricted 2 days + satiation 2 days. The restricted regime was achieved by offering fish 1% (maintenance ration) of their body weight per day adjusted after fortnightly weighing. African catfish showed partial compensatory growth under alternating periods of feed restriction and satiation feeding with significantly different values (P < 0.05) from fish fed in satiation throughout. However, significantly indifferent (P > 0.05) values of feed, protein, lipid and energy utilization were found under alternating periods of feed restriction and satiation feeding. Significantly higher (P < 0.05) feed intake was observed in treatment with satiation throughout than those in other treatments. All the feeding schedules showed no significant differences (P > 0.05) on body composition, organ indices, eviscerated carcass composition, viscera lipid and liver lipid. These studies reveals that C. gariepinus showed partial compensatory growth responses at alternating periods of restricted and satiation feeding.     

Effect of partial replacement of fish meal with soybean meal and feeding frequency on growth,feed utilization and body composition of juvenile Chinese sucker,Myxocyprinus asiaticus (Bleeker)

A factorial (2 × 4) feeding trial was conducted to investigate the effects of feeding frequency and partial replacement of fish meal (FM) with soybean meal (SBM) on the growth performance, feed utilization and body proximate composition of juvenile Chinese sucker. Two feed types including replacement of 30% FM (diet 1) with SBM (diet 2) were used. Triplicate groups of fish (average weight, 11.80 ± 0.19 g) were fed each feed type to visual satiation at four meals per day, three meals per day, two meals per day and one meal per day for 8 weeks. At the end of the feeding trial, the survival of fish was not significantly different among the treatments. Weight gain was affected by the feeding frequency. The highest weight gain was observed in fish fed with diet 1 at three meals per day. There existed a significant difference in daily feed intake (DFI), daily protein intake (DPI), feed conversion ratio (FCR) and protein efficiency ratio (PER) when the feeding frequency was increased from one or two to three or four meals per day (P < 0.001), but not by the feed types. For both two feed types, the highest DFI and DPI were observed at three meals per day. The highest PER was gained at four meals per day, while FCR was the least. The body proximate composition of fish was altered by feeding frequency. The crude lipid content increased with the increase in feeding frequency. Essential amino acids (EAAs) content showed no significant differences among different treatments. The present findings suggest that three feedings per day at visual satiation may be sufficient for the maximal growth performance of Chinese sucker grown from 11 to 45 g. Results also indicate that about 30% of FM protein can be replaced by SBM protein in Chinese sucker diets without adversely affecting growth.     

Effects of feeding frequency on growth,feed efficiency and body composition of juveniles Brazilian sardine,Sardinella brasiliensis (Steindacher 1879)

The Brazilian sardine is the most important fishery resource in Brazil. Their production has declined along the last 30 years due the overfishing, climatic and oceanographic phenomena. This study was carried out to determine the optimal feeding frequency for juvenile Brazilian sardine based on growth, feed efficiency, feed intake and body composition. Six feeding frequencies of one, two, three, four, five and six times a day were evaluated in triplicate tanks for 50 days. Fish with initial mean weight of 3.29 ± 0.56 g were fed daily to apparent satiation. The results showed that fish fed once daily had lower body weight gain, specific growth rate and condition factor (P < 0.05) compared with other treatments. The feed efficiency ratio in fish fed once daily was significantly higher (P < 0.05) than those fed two or more times a day. No significant differences were observed in the coefficient of variation in body weight (P > 0.05) among the treatments. Feed intake was directly proportional to the feeding frequency. Fish fed once daily showed lower hepatosomatic and mesenteric fat indices (P < 0.05) than the other treatments. Neither protein nor ash content of fish were significantly (P > 0.05) affected by feeding frequency. However, the lipid content increased with feeding frequency. The results suggest that the optimal feeding frequency for juvenile Brazilian sardine is at least twice daily.     

Effects of feeding rates on growth and production of Nile tilapia, common carp and silver carp polycultured in fertilized ponds

Abstract In an attempt to identify appropriate feeding rates for multispecies of fish raised in fertilized earthen ponds, the present work was conducted over a 19‐week experimental period to establish the growth performance, production and body composition of Nile tilapia, common carp and silver carp fed 0.0%, 0.5%, 1.0%, 3.0%, 5.0% biomass and to apparent satiation (treatments). Twelve ponds were stocked with a similar number and weight of each fish species. Two ponds were assigned to each of the treatments, and a 25% protein pelleted fish feed was used to feed fish at the specified rate of feeding. At the end of the experiment, growth, weight gain, survival, yield and body composition of fish groups were affected by the treatments. The economic effectiveness also varied among treatments. The most conspicuous attribute of the feeding rates was its lack of influence on growth (g day^?1), weight gain (g per fish), yield (kg ha^?1) or body composition of silver carp. The results of whole‐body proximate analysis indicated that various feeding rates had either an irregular pattern or no effects on the protein and ash gain per 100 g of fish body weight (bw) gain. The most notable exceptions were significant (P < 0.05) increases in body fat and gross energy gains in Nile tilapia, common carp and silver carp accompanied by decreases in percentages of moisture (but not in silver carp) as feeding rate increased. Among the six different feeding levels, feeding to apparent satiation (feed amount was equivalent to 2.67% of fish bw day^?1) appeared to be optimal, as it significantly (P < 0.05) supported the highest fish production, income and net profit compared with all other treatments except for the 3% feeding level, for which the differences in those measurements were comparable.     

Effect of feeding frequency on growth performance,blood metabolites,proximate composition and digestive enzymes of Lebranche mullet (Mugil liza) Juveniles

This study verified the effects of feeding frequency on growth, blood metabolites, digestive enzyme activities (alkaline protease, acid protease, amylase and lipase) and proximate composition of Lebranche mullet juveniles. Fish with initial weight of 13.6 ± 0.7 g were distributed in twelve tanks and fed one, three, five and seven times per day to apparent satiation for 60 days. While the final weight of fish fed only once a day attained just 15.4 ± 0.7 g, those fed five or seven times per day reached 54.0 ± 12.1 and 55.9 ± 6.1 g respectively. The feed consumption also increased at high frequencies, but feed efficiency was higher (76.7 ± 11.7%) when mullets were fed three times per day. In general, increasing feeding frequencies also increased blood content of metabolites (total protein, glucose, triglycerides and cholesterol), possibly due to increased intake and absorption of nutrients. The response of digestive enzymes correlated with feeding efficiency, with higher activity in fish fed three or five times per day. Concerning whole‐body proximate composition, no significant difference was observed in protein, but lipid content increased significantly with feed frequency. Based on growth performance and biochemical responses, we recommend feeding Lebranche mullet juveniles three to five times per day.     

Nucleotide promotes feed intake and protein utilization via regulating the gene expression of feeding and nitrogen metabolism in juvenile Chinese perch (Siniperca chuatsi)

Nucleotide (NT) could enhance growth, feeding and immunity in higher vertebrate and fish. Chinese perch (Siniperca chuatsi) refuse artificial diet in natural water, whereas the NT might promote its feeding of domestication diet. The present study was designed to investigate the effect of dietary NT on growth, feed intake, feed utilization, body composition, serum biochemistry and nitrogen metabolism in juvenile Siniperca chuatsi. 0, 0.5, 1.0, 1.5, 2.0 and 4.0 g NT kg^?1 diet were supplemented in each diet, respectively. Triplicate groups of Chinese perch (36.21 ± 0.98 g) were fed twice a day to apparent satiation for 8 weeks. The results showed that fish fed with 1.5 g NT kg^?1 diet had the highest weight gain (WG), specific growth rate, feed efficiency, feed intake, protein efficiency ratio and protein retention efficiency. The crude protein content in whole body was highest in fish fed the diet containing 1.5 g NT kg^?1 diet. Dietary NT supplementation significantly increased the neuropeptide Y gene expression and significantly decreased the agouti‐related protein and pro‐opiomelanocortin gene expressions in brain. NT supplementation decreased urea nitrogen content, aspartate aminotransferase (AST) and alanine aminotransferase activities in serum. The hepatic AST activity was increased first and then decreased, and the highest activity was observed in fish fed with 1 g NT kg^?1 diet. Inversely, the activity of glutamate dehydrogenase (GDH) in liver and adenosine 5′‐monophosphate deaminase in muscle decreased first and then increased, and the lowest activity was observed in fish fed with 1.5 g NT kg^?1 diet. Similarly, the gene expression levels of GDH and arginase in liver were lowest in fish fed with 1.5 g NT kg^?1 diet. Based on the broken‐line regression analysis of WG in the present experimental condition, 1.44 g NT kg^?1 diet was the optimum supplementation level in juvenile Siniperca chuatsi.     

Effect of feeding frequency on growth,feed utilization,body composition and waste output of juvenile golden pompano (Trachinotus ovatus) reared in net pens

A 6‐week feeding trial was conducted to examine the effect of feeding frequency on growth, feed utilization efficiency, body composition and waste output of juvenile golden pompano Trachinotus ovatus reared in net pens. Fish (10.3 ± 0.5 g) were either fed a formulated diet containing 48.4% crude protein and 5.7% crude lipid at 0.5, 1, 2, 3 or 4 meals per day or fed a raw fish feed at two meals per day as a control. The weight gain (WG) increased with increasing feeding frequency from 0.5 to 3 meals per day (P < 0.05), but did not significantly change with the further increase in feeding frequency from 3 to 4 meals per day (P > 0.05). The feed intake (FI) was lower in fish fed at 0.5 or 1 meal per day than in fish fed at 2, 3 or 4 meals per day (P < 0.05). No significant differences were found in the feed conversion ratio (FCR), nitrogen retention efficiency (NRE), condition factor (CF), nitrogen waste output (NWO) and phosphorus waste output (PWO) between fish fed at 1, 2, 3 or 4 meals per day (P > 0.05), whereas no significant difference was found in the phosphorus retention efficiency (PRE) among the feeding treatments (P > 0.05). The body lipid content increased, whereas the contents of moisture and ash decreased, with the increase in feeding frequency (P < 0.05). At the same feeding frequency, fish fed the formulated diet exhibited lower FI, FCR, HSI, body moisture content, NWO and PWO, but higher NRE, PRE, body lipid content and body phosphorus content than those of fish fed the raw fish feed (P < 0.05). These results suggest that the formulated diet can satisfy nutrient requirements of juvenile golden pompano reared in net pens, and the suitable feeding frequency is 3 meals per day.     

Feed intake,growth, feed utilization,body composition and waste output of juvenile hybrid bream at different feeding frequencies

An eight‐week feeding trial was conducted to evaluate the feed intake, growth, feed utilization, body composition and waste output of juvenile hybrid bream at different feeding frequencies (0.5, 1, 2, 3 or 4 meals/day). Fish (initial body weight of 10.6 ± 0.8 g) were fed to satiation at each feeding. The test diet contained 336 g/kg crude protein and 79 g/kg crude lipid. The weight gain significantly increased with increase in feeding frequency from 0.5 to 3 meals/day (p < 0.05) and afterwards did not change with feeding frequency from 3 to 4 meals/day (p > 0.05). The feed intake increased with increase in feeding frequency (p < 0.05). Fish fed at 3 meals/day exhibited the lowest feed conversion ratio and waste output of nitrogen and phosphorus, however, the highest nitrogen retention efficiency (p < 0.05). No significant differences were found in the phosphorus retention efficiency, the body composition of crude protein, ash and phosphorus among all the feeding frequencies (p > 0.05). The body lipid content increased, whereas the content of moisture decreased, with the increase in feeding frequency (p < 0.05). The present study reveals that the optimum feeding frequency is 3 meals/day for hybrid bream.     

Growth performance,body composition and metabolic response to feeding rates in juvenile Brazilian sardine Sardinella brasiliensis

A 6‐week growth trial was conducted to evaluate the effects of feeding rate on growth performance, body composition, plasma metabolites and enzyme activities, and to determine the optimal feeding rate for juvenile Brazilian sardine. Fish were fed at six feeding rates, 2, 4, 6, 8, 10% BWday^?1 (body weight per day) and until satiation (10.3% BWday^?1). The survival of fish fed at 2%–6%BWday^?1 was significantly higher (p < .05) than the survival of fish fed at the other feeding rates. The final body weight and specific growth rate significantly increased (p < .05) with increasing feeding rates while feed utilization decreased. Total proteins, cholesterol and triglycerides concentrations increased significantly with increasing feeding rates; however, there was no significant effect on glucose levels. Body protein and ash contents were not affected by the feeding rates. Whole‐body lipid content increased significantly as the feeding rate increased, while moisture content had an opposite trend. Proteases and amylase activities significantly decreased with increasing feeding rates, while lipase activity was not influenced by the feeding rate. Our results suggest that low feeding rates stimulate mobilization of metabolites to supply energy for the maintenance of overall metabolism and digestive enzyme activities increase to enhance feed utilization. The optimum feeding rate of juvenile Brazilian sardine based on PRR as determined by the second‐order polynomial regression was 5.45% BWday^?1.     

Effect of Dietary Lipid Level and Feeding Frequency on the Growth,Feed Utilization,and Body Composition of Juvenile Spotted Seabass,Lateolabrax maculatus

A 6‐wk feeding trial was conducted to evaluate the effects of different dietary lipid levels and feeding frequencies on the growth performance, feed utilization, and body composition of juvenile spotted seabass, Lateolabrax maculatus. Two experimental diets were prepared with two different dietary lipid contents, low lipid (7%; LL) and high lipid (14%; HL). Each diet was fed to triplicate groups of fish (5.5 ± 0.01 g) to apparent satiation at three meals per day, two meals per day, one meal per day, and one meal every 2 d, respectively, for 6 wk. Fish growth performance in terms of weight gain (WG) and specific growth rate (SGR) was significantly affected by frequency of feeding, with increasing values as feeding frequency increased up to twice daily, regardless of dietary lipid content. In addition, fish fed the diet with the HL level (14%) showed significantly higher WG and SGR than those fed the LL diet (7%) at all the feeding frequencies tested. Feed efficiency (FE) and protein efficiency ratio (PER) were affected by both dietary lipid level and feeding frequency. FE and PER values were significantly higher in fish fed the HL diet and/or when fish were fed twice or thrice a day. However, daily feed intake and daily energy intake were significantly affected only by feeding frequency and were significantly reduced when the fish were fed only once every 2 d compared with those fed more frequently. Whole‐body moisture content of fish tended to decrease with increasing dietary lipid level and frequency of feeding. In contrast, whole‐body lipid content increased in fish as dietary lipid level and feeding frequency increased. Consequently, we can conclude that feeding spotted seabass twice daily to apparent satiation is acceptable and sufficient to achieve good growth and FE, as fish performance was not significantly enhanced when feeding was increased from two to three times daily.     

Utilization of dietary starch by juvenile white sea bream Diplodus sargus at different feeding frequencies

To assess the effect of feeding frequency on the utilization of dietary starch by white sea bream juveniles, triplicate groups of fish were fed an experimental diet (400 g kg^?1 protein, 140 g kg^?1 lipids and 350 g kg^?1 pregelatinized maize starch) to apparent visual satiation 2, 3 or 4 times a day for 63 days. Growth performance, feed utilization efficiency, glycaemia, cholesterolaemia, plasma triacylglycerides, liver lipids and glycogen content were unaffected by feeding frequency. α‐Amylase activity increased from the pyloric caeca to the posterior intestine and was higher in fish fed twice a day than in fish fed 3 or 4 times a day. Hepatic glucokinase (GK) activity decreased with the increase in feeding frequencies, whereas fructose‐1,6‐bisphosphatase (FBPase) activity increased. Hepatic glucose‐6‐phosphate dehydrogenase and glutamate dehydrogenase activities were unaffected by feeding frequency. Overall, feeding frequency did not improve white sea bream dietary starch utilization. α‐Amylase, GK and FBPase activities responded to dietary starch consumed at each meal, denoting a good metabolic adaptation of the fish to the feeding conditions.     

The optimum dietary protein level for the Mexican cichlid Cichlasoma urophthalmus (Günther): a comparison of estimates derived from experiments using fixed-rate feeding and satiation feeding

Optimum dietary protein levels of young Cichlasoma urophthalmus (Günther) of 0.3 g mean weight were determined at 28°C using two methods, a fixed feeding rate of 6% body weight per day and satiation feeding. In the fixed rate trials nine isoenergetic diets were formulated with protein levels ranging from 347 to 561 g kg^?1 using brown fish meal (anchovy) as the only protein source. In the satiation feeding trials, ten diets were formulated based on brown fish meal (mackerel) ranging from 0 to 450g kg^?1 protein. When fish were fed a fixed rate diet, the best absolute growth was obtained with diets between 435 and 560 g kg^?1 protein. Broken-line analysis showed that, in terms of weight gain (%), the optimum protein level was about 453 g kg^?1. When fish were fed to satiation, the best absolute growth was obtained with the 383 g kg^?1 protein diet, and broken-line analysis suggested an optimum of about 325 g kg^?1. The difference between the two results, using the two techniques, is very marked. The probable mechanism underlying these data is discussed.     

The effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus L.

Four experiments were conducted to investigate the effects of feeding frequency on growth of juvenile Atlantic halibut, Hippoglossus hippoglossus L. Fish (22–75 g) fed three (3 ×) or five times per day (5 × day^?1) under constant light and temperature (13±1°C) consumed significantly more feed than fish fed 1 × day^?1 but by the end of the experiment only fish fed 5 × day^?1 were heavier and had greater specific growth rates (SGR). Under simulated winter conditions (9L:15D, 5±1°C), halibut (～300 g) fed every other day consumed more feed, had a greater SGR and final weight compared with fish fed every third day. Feed conversion ratios were not different among treatment groups in any of the experiments. These results suggest that growth rates may be improved by feeding juvenile halibut more than 1 × day^?1.     

A comparative study of growth and feed utilization efficiency of sex-reversed diploid and triploid Nile tilapia, Oreochromis niloticus L.

Growth performance, survival and feed utilization of diploid (2n) and triploid (3n) sex‐reversed male and female Nile tilapia were evaluated at maintenance feeding (1% body weight (BW) day^?1), fixed feeding (3% BW day^?1) and apparent satiation feeding levels in a freshwater recirculation system comprised of thirty‐six 1‐m³ concrete tanks at the Asian Institute of Technology, Bangkok, Thailand. Triploid Nile tilapia (3n) was produced by subjecting fertilized diploid (2n) tilapia eggs to heat shock. After hatching, fish were sex‐reversed to all‐male and all‐female populations by oral administration of 17 α‐methyltestosterone (60 mg kg^?1 feed) and ethynylestradiol (100 mg kg^?1 feed) respectively. There was significantly higher growth with increased ration levels in both male and female groups. There were no significant differences in final BW, specific growth rate, survival rate, feed conversion ratio and protein efficiency ratio between diploid and triploid fish. Triploids had lower gonad weights than diploids, and this was particularly evident at the satiation feeding level. Triploid fish had a significantly higher apparent net protein utilization and percentage of gutted weight than diploids at all feeding levels. Higher protein utilization efficiency of triploids might be an advantage for commercial tilapia culture but further research is necessary to make such a conclusion.     

Effect of feed composition and feeding frequency on growth, feed utilization and nutrient retention in juvenile Atlantic cod, Gadus morhua L.

Juvenile Atlantic cod (Gadus morhua) were fed extruded feeds formulated to contain 360–660 g kg^?1 protein, 80–280 g kg^?1 lipid and 80–180 g kg^?1 starch at feeding frequencies of either once per day or every second day to satiation. The trial was conducted at 8 °C and lasted for 28 weeks during which fish were weighed five times at regular intervals. Sampling for proximate analysis was performed at the start, after 12 weeks and at the end of the trial. Fish grew from an average weight of 192 g to between 750 and 866 g, with growth being negatively affected by low dietary protein concentration. High dietary starch concentrations had some negative effects on growth, whereas changes in dietary fat concentration had no significant effect on growth. Liver indices (at the end of the experiment) varied between 80 and 170 g kg^?1, and there was a negative correlation between the ratio of protein to fat and liver index. Feed conversion ratio (FCR) ranged between 0.74 and 0.88, and feed utilization improved with increasing concentrations of dietary protein and fat. Increasing dietary starch concentrations resulted in poorer feed utilization. To achieve good growth and protein retention, and avoid excessive liver size in juvenile cod, feeds should contain 500–600 g kg^?1 crude protein, 130–200 g kg^?1 lipid and <150 g kg^?1 starch.     

Feeding,growth, and blood chemistry of the tambaqui (Colossoma macropomum) held under self-feeding and time-restricted automatic feeding conditions

This work evaluated the effects of food frequencies and self-feeding on the behavior, performance, and blood biochemistry of Colossoma macropomum. Juveniles weighing 3.63?±?0.05 g were distributed in 27 aquariums (40 L), with six fish per aquarium, to evaluate nine treatments in three replications in a 12L:12D photoperiod. The treatments were 24-h self-feeding (SF); daytime self-feeding at will (SFD); nighttime self-feeding at will (SFN); and feeding at fixed frequencies of two (2D), four (4D), and six times (6D) daytime and twice (2 N), four (4 N), and six times (6 N) nightly. The treatments were offered in automatic feeders, with fixed frequencies programmed. Extruded commercial feed, with 46% protein, was used. The experimental period was 40 days. In the SF treatment, the animals exhibited 95.7% nocturnal and 4.3% diurnal feeding activity (p?<?0.05). In the treatment SFD and SFN, the animals showed feeding activity throughout the day and night. Final weight, weight gain, and total feed intake were higher for animals at fixed daytime and nighttime frequencies (p?<?0.05). Feed conversion was better for animals in SF, SFD, 4D, SFN, and 4 N (0.89, 0.76, 0.91, 0.85, and 0.88, respectively) (p?<?0.05). Cholesterol and high-density lipoproteins were lower for fish in SF, SFN, 2 N, 4 N, and 6 N (p?<?0.05). SF treatment animals had lower triglyceride content, 154.20 mg dL^?1 (p?<?0.05). Colossoma macropomum has nocturnal food preferences, however, with remarkable plasticity. Juveniles of this species fed four times during the day or night show good performance. Dietary patterns influenced the blood metabolic indicators of this species and the periods studied.

     

Effects of different feeding regimes on juvenile black rockfish (Sebastes schlegilii) survival,growth, digestive enzyme activity,body composition and feeding costs

The objective of this study was to establish a proper feeding regime for juvenile black rockfish (Sebastes schlegilii) intended for stock enhancement. We used a combined experimental design to assess the effects of different feeding rates (1%, 3% and 5% body weight per day (BW/day)) and feeding frequencies (apparent satiety or restricted feeding 1 to 3 times daily) on survival, growth, digestive enzyme activity, body composition and feeding costs over 50 days, from newly weaned (initial average weight 1.5 ± 0.2 g) to release size. The results showed that feeding rate significantly affected fish growth, feed utilization and body composition. The highest feed conversion ratio was at 3% BW/day. Increased feeding rates resulted in enhanced growth and higher body lipid content, but this was also accompanied by decreased contents of moisture, protein and ash. With feeding to apparent satiety, increased feeding frequency resulted in higher growth performance and enhanced intestinal lipase activity but decreased gastric protease activity. There were no growth improvements or effects on digestive enzyme activity and body composition with increasing feeding frequency (from one to three times daily) under a fixed‐quantify feeding (3% BW/day). Feed costs increased with increasing feeding rates or apparent satiety feeding frequencies and were associated with shorter growth times to reach a suitable size for release. Our study suggests that a feeding rate of 3% BW/day is the best feeding regime for proper growth and reduced feed costs in juvenile black rockfish before releasing for stock enhancement.     

Feed management and stocking density of the endangered wild zebra pleco: Implications for captive breeding

Due to the economic potential of Hypancistrus zebra in the ornamental fish market and its current classification as an endangered species in its natural occurrence sites, the present study sought to determine a suitable feed management strategy and stocking density to allow for an adequate captivity maintenance of this fish species. Three experiments were conducted as follows: (1) feed preference (artemia Artemia sp., shrimp Litopenaeus vannamei, fish Cynoscion spp. or mussel Perna perna); (2) determination of feeding rate (5% and 10% live weight day^?1) and frequency (1, 2 or 3 meals. Day^?1); and (3) evaluation of stocking density (0.25, 0.50, 1.00 and 2.00 g/L). Zebra pleco did not present the characteristic buccal scraping behaviour on the feed, commonly seen in other Loricariids. Artemia was the preferred diet followed by fish, shrimp and mussels. The frequency of two daily meals and the feeding rate of 10% live weight day^?1 allowed for an improved zootechnical performance. Zebra pleco showed enhanced specific growth rate at the density of 2 g/L. Our results suggest that, to improve the zebra pleco rearing conditions, it should be maintained at a density of 2 g/L, fed two daily meals at a feeding rate of 10% live weight day^?1. These findings correspond to useful information for an adequate management of this species and could assist in the supply of healthy specimens to the ornamental fish market as well for the restocking of declining wild populations.     

Effects of dietary protein and lipid levels on growth,feed utilization and body composition in red‐tailed catfish juveniles (Hemibagrus wyckioides,Chaux & Fang 1949)

A feeding trial was conducted in a recycling water system during 10 weeks to determine the optimal protein to lipid ratio in Asian red‐tailed catfish (Hemibagrus wyckioides). Six diets of two protein levels (390 and 440 g kg^?1) with three lipid levels (60, 90 and 120 g kg^?1) were formulated. Fish (1.96 g) were fed six diets with four replicates to apparent satiation at a stocking density of 50 fish per tank (500 L). Faeces were collected in cultured tanks at the end of the feeding trial for digestibility measurement. Significantly, improved growth performances (P < 0.01) and higher feed utilization (P < 0.001) were observed in fish fed with higher lipid diets. However, higher protein diets did not significantly improve fish growth but they reduced FCR (P < 0.001) and protein efficiency ratio (P < 0.01). Higher lipid diets also resulted in significantly increased adipose‐somatic index, carcass fat and reduced moisture of the fish. The study revealed the protein sparing effect of dietary lipid in the catfish and highest growth performance was found by fish fed 390 g kg^?1 protein and 120 g kg^?1 lipid diet with P/E ratio of 20.48 mg protein kJ^?1. DP/DE ratio for maximal growth rate in diets was 21.48 mg protein kJ^?1.     

Compensatory growth response of Sparus aurata following different starvation and refeeding protocols

A feeding trial evaluated the influences of different cycles of starvation and refeeding protocols for 7 weeks on growth and feed intake in 14‐g gilthead sea bream, Sparus aurata. Following 7 weeks of alternated cycles, all the groups were fed to apparent satiation for a further 3 weeks. Three groups of fish were fasted for 2, 4 or 7 days (S2, S4 and S7, respectively) and then refed until their relative feed intake differed by less than 20% of fed controls until the end of the week 7, while a fourth group (S7/Rf14) experienced three cycles, each consisting of 1 week of food deprivation followed by 2 weeks of satiation feeding. Control (C) fish were fed to satiation throughout the trial. The fish were fed a sea bream diet (450 g kg^?1 crude protein) according to the protocols, twice a day for 7 weeks. Growth performance and feed intake in continuously fed control group were significantly higher than those of the deprived groups (S2, S4, S7 and S7/Rf14) (P < 0.05). Weight gain highly correlated with total feed intake (R² = 94), and feed efficiency was the highest in the control group than other deprived groups (P < 0.05). The juveniles of gilthead sea bream demonstrated only a partial compensation during the cycling period and even after being fed to satiation for another 3 weeks. The convergence of growth trajectories and subsequent hyperphagic responses of the groups fed according to protocols are discussed in terms of possible costs of compensatory growth.