The dietary protein requirement of a bagrid catfish, Mystus nemurus (Cuvier & Valenciennes), determined using semipurified diets of varying protein level

Triplicate groups of Mystus nemurus (Cuvier & Valenciennes) were fed isoenergetic semipurified diets containing seven dietary protein levels from 200 to 500 g kg^–1 diet for 10 weeks. Dietary protein was supplied by graded amounts of a protein mixture (tuna muscle meal:casein:gelatine) at a fixed ratio of 50:37.5:12.5. Mystus nemurus fingerlings of initial weight 7.6 ± 0.2 g were fed close to apparent satiation at 2.5% of their body weight per day in two equal feedings. Growth performance and feed utilization efficiency increased linearly with dietary protein level from 202 to 410 g kg^–1 diet and declined with protein levels of 471 g kg^–1 diet or above. Protein efficiency ratio and apparent net protein utilization started to decline when the fish were fed with dietary protein levels exceeding 471 g kg^–1 diet. Fish fed with lower protein diets (202–295 g kg^–1 diet) had significantly ( P  < 0.05) higher carcass lipid content compared with fish fed with higher protein diets. Carcass lipid contents were inversely related to moisture content. Dietary protein did not significantly affect fish carcass protein and ash content. Using two-slope broken-line analysis, the dietary protein requirement for M. nemurus based on percentage weight gain was estimated to be 440 g kg^–1 diet with a protein to energy ratio of 20 mg protein kJ^–1 gross energy. This level of protein in the diet is recommended for maximum growth of M. nemurus fingerlings weighing between 7 and 18 g under the experimental conditions used in this study.     

Apparent digestibility coefficients for common feed ingredients in formulated diets for tropical catfish, Mystus nemurus (Cuvier & Valenciennes)

Abstract Apparent digestibility coefficients were determined for six feedstuffs, subsequent to their processing into pelleted feed for tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes), using a reference diet and test diets composed of 70% reference diet and 30% test ingredient. It was found that most ingredients were fairly well digested except maize and chicken viscera. Digestibility coefficient for protein (P), dry matter (DM) and energy (E) were: (1) fish meal: 97·8% P,97% DM. 77·88% E: (2) soybean meal: 86% P,95·55% DM, 67·89% E: (3) rice bran: 81% P,85·81% DM, 67·93% E: (4) copra meal: 79·90% P, 86% DM, 71·89% E: (5) maize: 51·93% P, 49·0% DM, 63·40% E and (6) chicken viscera: 37% P,29% DM, 52% E. Digestibility coefficients for feedstuffs indicated that animal protein product, such as fish meal and grain by-product, such as rice bran were more digestible than starchy and fibrous feed, e.g. maize. Chicken viscera was poorly digested largely due to inefficient processing. As most feedstuffs were well digested, ingredient selection should, therefore, be based primarily on their protein content, amino acid composition and palatability.     

Improved survival and growth performances with photoperiod and feeding schedule manipulation in bagrid catfish Mystus nemurus (Cuvier & Valenciennes 1840) larvae

Manipulation of photoperiod: 24 h light (24L), 12 h light:12 h dark (12L:12D) and 24 h dark (24D); and feeding schedules: day and night feeding (DNF), day feeding (DF) and night feeding (NF) was conducted to determine effects on survival, cannibalism and growth of larval bagrid catfish Mystus nemurus 2–14 days after hatching (dAH). Photoperiod insignificantly affected all parameters. Feeding schedule significantly affected survival and total length at 6 (P < 0.049; P < 0.009), 10 (P < 0.033; P < 0.000) and 14 dAH (P < 0.013; P < 0.000), respectively, but affected cannibalism at 10 (P < 0.043) and 14 dAH (P < 0.013). Survival for DNF was significantly higher than DF. Cannibalism for DNF was significantly lower than NF at 10 and 14 dAH. Total length for DNF was significantly higher than DF and NF at 10 and 14 dAH. At 14 dAH, feeding schedule significantly affected feed intake, final weight and coefficient of variation. For feed intake and final weight, DNF was significantly higher than DF and NF. For coefficient of variation, NF was significantly higher than DF. This study suggests that larval bagrid catfish can be reared at 24L, 12L:12D or 24D but should be fed day and night for improved growth, survival and reduced cannibalism.     

In vivo and in vitro protein digestibility in juvenile bagrid catfish Mystus nemurus (Cuvier and Valenciennes 1840) fed soybean meal‐based diets

In vivo and in vitro protein digestibility of 0% to 60% soybean meal protein (SBM) substitution from fishmeal protein was conducted for bagrid catfish Mystus nemurus juveniles. Seven experimental diets containing 35% protein and 15% lipid were fed to bagrid catfish to determine the in vivo protein digestibility. In vitro methods were determined using pH stat, pH shift, spectrophotometric assay and sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) with different enzyme mixtures (crude intestinal extract of bagrid catfish, Lazo 1‐enzyme, Hsu 3‐enzyme, Saterlee 4‐enzyme). In vivo and in vitro protein digestibility decreased with increased SBM protein substitution with highest tolerance level of 10% (in vivo). pH stat and pH drop methods showed the highest degree of hydrolysis (DH) and relative protein digestibility (RPD) using Saterlee 4‐enzyme system. However, pH stat method showed highest correlations (r² = 0.9263) with the in vivo results using crude intestinal enzyme extract compared to other enzyme systems. The highest correlation of the in vitro methods using crude intestinal enzyme extracts of bagrid catfish was determined using spectrophotometric assay (r² = 0.9284) followed by pH stat (r² = 0.9263), SDS‐PAGE (r² = 0.8348) and pH drop (r² = 0.6777). All the in vitro methods tested are suitable to rapidly determine protein digestibility for bagrid catfish except for pH drop.     

Improved survival and growth performances with stocking density manipulation and shelter availability in bagrid catfish Mystus nemurus (Cuvier & Valenciennes 1840) larvae

Manipulation of stocking densities (10, 20, 30, 40 and 50 larvae L^?1), each with or without the presence of shelter was conducted to determine the effects on survival, cannibalism and growth performances of larval bagrid catfish Mystus nemurus (Valenciennes 1840) from 2 to 14 days after hatching. This study revealed that stocking density significantly affected survival, cannibalism, total length, feed intake, specific growth rate and final weight of bagrid catfish larvae. Significantly higher survival was observed at moderate stocking density of more than 20 but less than 50 larvae L^?1. Survival was significantly low beyond this threshold and was the lowest at 10 larvae L^?1, coincides with the highest cannibalism. Total length, feed intake, specific growth rate and final weight were significantly higher at 10 larvae L^?1. Shelter significantly improved total length and feed intake. No significant effects of stocking density and shelter were observed on the apparent feed conversion ratio and coefficient of variation. There was also no significant interaction between stocking density and shelter in all parameters. This study suggests that bagrid catfish larvae could be cultured at more than 20 but less than 50 larvae L^?1 with the availability of shelter for optimal larviculture condition.     

Reproductive biology of a tropical catfish, Mystics nemurus Cuvier & Valenciennes, in Chenderoh reservoir, Malaysia

Abstract. The reproductive biology of a popular and abundant freshwater catfish, Mystus nemurus Cuvier & Valenciennes, was examined, including sex ratio, gonadosomatic index, ova diameter and fecundity. The numerical ratio of male to female was 1:1.06 and was not significantly different (P > 0.05). Mean female gonadosomatic indices (GSI) in April and September corresponding to north-east and south-west monsoons were significantly different (P < 0.05) from the dry season (May, June, July and August). Thus the apparent GSI maxima in April and September were indicative of peak spawning period. However, there were no significant differences (P > 0.05) in the fluctuation of the measure of GSI except for those in the dry months, which probably suggested the existence of a protracted breeding season. Mean male GSI in February and November were similarly significant (P < 0.05) to the dry season, although not statistically different (P > 0.05) from those of January, March, April, July, August, October and November. This was probably attributable to an extended breeding period with spawning peaks in February and November corresponding to early and late monsoons. The aseasonal reproduction is common in tropical fishes. GSI were positively correlated with rainfall and water level fluctuations. Fecundity varied from a minimum 6900 to a maximum 93510 in specimens with total lengths of 34.8cm and 45.0cm respectively. Fecundity was found to increase linearly with length and weight and was significantly different (P < 0.05) from them.     

Effect of population density on the growth, feed and protein conversion efficiency and biochemical composition of a tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes)

Abstract. Six groups of tropical freshwater catfish, Mystus nemurus (Cuvier & Valenciennes)(mean weight. 20·45 ± l·5g), were reared in 0·34m³ fibreglass tanks at different stocking densities (105, 195, 285, 375, 465 and 555 specimens/m³ water) for 84 days. The objective of the study was to determine the effect of various stocking densities on the growth, nutrition, biochemical composition and survival of M. nemurus. The lowest growth rate appeared in fish at the highest density and the highest was observed in fish stocked in moderate density of 285 and 375 fish/m³ water. Fish production was also lower at relatively low stocking densities of 105 and 195 fish/m³. Food conversion ratio (FCR), protein efficiency ratio (PER) and biochemical composition of M. nemurus indicate that there exists an optimum stocking density which lies between 285 and 375 fish/m³.     

The effect of varying dietary protein level on the growth, food conversion, protein utilization and body composition of tropical catfish Mystus nemurus (C. & V.) cultured in static pond water system

Tropical catfish, Mystus nemurus (C. & V.) (25.89 ± 0.7 g) were stocked semi-intensively in 0.03-ha earthen ponds at the rate of 10 000 ha”^-1 and fed six iso-energetic practical diets ranging from 27% to 50% protein for 8 weeks. Each diet was fed in three replicate ponds twice daily to satiation. Experimental fish were also reared extensively, in control ponds, without supplementary feed. Fish fed the 42% protein diet had the highest standing crop, weight gain and protein utilization values and the differences from other diets were statistically significant (P > 0.05). Protein efficiency ratio (PER) decreased as dietary protein increased. The experiment indicated that natural food organisms contributed to some degree if not significantly to the catfish production. Weight gain, food conversion ratio (FCR). PER and SGR (specific growth rate) indicated that a 42% protein diet with digestible protein-to-energy ratio (D/E) of 27.57 mg kj^_1 produced maximum growth in the static pond system.     

Dietary administration of androgens induces sterility in the female-heterogametic black molly, Poecilia sphenops (Cuvier & Valenciennes, 1846)

Treatment of newly born Poecilia sphenops (Cuvier & Valenciennes, 1846) with 50 mg 17α-methyl-testosterone or 200 mg androstenedione per kg diet for 30 days induced a maximum of 59% males; attempts to increase masculinization by increasing dose or treatment duration resulted in higher mortality. The growth of the treated males was significantly (25-53% retarded. Anabolic enhancement of relative growth (percentage of control) of the treated males and females was apparent in juveniles but not in adults. Hormonal induction of masculinization impaired the gonadal development and courtship activity, and led to the production of sterile males and females.     

Development of a pelleted feed for juvenile tropical spiny lobster (Panulirus ornatus): response to dietary protein and lipid

Critical to the development of a cost‐effective feed for the tropical spiny lobster Panulirus ornatus is knowledge of its response to the protein and lipid (or energy) content of the feed. An experiment of 12 weeks duration was carried out to examine growth responses of juvenile lobsters to pelleted diets that provided six crude protein (CP) levels [320–600 g kg^?1 dry matter (DM)] and two lipid levels (nominally 60 and 100 g kg^?1 DM). Lobsters (mean initial weight of 1.8 g) were held in groups of nine or 10 animals in 24 × 350 L tanks, fed twice daily at a restricted level, and maintained at 28 °C. Maximal growth responses occurred at dietary CP contents of 474 g kg^?1 for the 60 g kg^?1 lipid series and 533 g kg^?1 for the 100 g kg^?1 lipid series. A second experiment, of 4 weeks duration, compared two dietary treatments: a mixture of two of the best diets from the first experiment, and a commercial shrimp (Penaeus japonicus) feed. Lobsters were held under the same experimental conditions as in the first experiment, but were fed to excess twice daily. Their growth was significantly greater (P < 0.05) on the shrimp feed (0.68 g week^?1) than on the laboratory‐pelleted diets used in the main study (0.32 g week^?1). The results indicate that the optimal dietary protein and lipid content of the diet for P. ornatus is about 530 and 100 g kg^?1, respectively.     

Lernea cyprinacea L. (Copepoda: Caligidea) in Helostoma temmincki Cuvier & Valenciennes: the dynamics of resistance in recovered and naive fish

Abstract. All recovered and naive Helostoma temmincki lost their infections 30 days after homologous challenge with Lernaea cyprinacea. It is suggested that there is acquired protective immunity in recovered fish. No parasites were detected in five out of 20 recovered fish when the infective challenge dose was low; all naive fish (20) in the same tank were infected. In another experiment, all nine recovered fish were infected when the challenge infective dose was high. Recovered fish lost their infections (i.e. number of fish with no parasites and the number of parasites rejected) much faster than naive fish and this was very evident in the first 2 weeks after challenge. Parasites on recovered fish lost more egg sacs than naive fish during the same period. Eggs from parasites on recovered fish either did not hatch or were not infective or only caused a very low transitory infection in naive fish. It is suggested that, if no naive fish are introduced into a closed system for a period (and this has to be determined under field conditions) after an outbreak, then there will be no infective larvae in the water and the system will now be safe for restocking. This novel approach to control of the parasite L. cyprinacea and the spread of this disease will have to be carefully tested under field conditions.     

Preliminary study of the performance of crude illipe oil (Shorea macrophylla) as a dietary lipid source for riverine cyprinid Tor tambroides

Fisheries Science - Illipe Shorea macrophylla is a riverine fruit naturally eaten by Malaysian mahseer Tor tambroides and other riverine cyprinids. The effects of crude illipe oil on the growth...     

Evaluation of cold‐pressed flaxseed oil as an alternative dietary lipid source for juvenile sablefish (Anoplopoma fimbria)

This study was undertaken to determine the suitability of using cold‐pressed flaxseed oil (FO) as a major source of lipid in place of anchovy oil (AO) in the diet of juvenile sablefish (Anoplopoma fimbria), a relatively new marine species to aquaculture. Sablefish were fed one of four diets twice daily to satiation for 15 weeks. The test diets were identical in composition, except for the source of supplemental lipid which was either 100% AO (100AO), or increasing replacement of AO with FO i.e., 75AO:25FO, 50AO:50 FO or 25AO:75FO. Sablefish growth parameters, whole body and fillet proximate constituent concentrations and apparent digestibility coefficients were uninfluenced by diet treatment. There were also no adverse effects of the diet treatments on fish health, as determined from analysis of various haematological and innate immunological parameters. Terminal fillet fatty acid compositions generally reflected the dietary fatty acid compositions, while flesh contaminant concentration decreased with increasing dietary flaxseed oil content. Results indicated that FO may comprise up to 75% of the supplemental lipid in a grower diet for sablefish, while still providing humans with a rich dietary source of highly unsaturated fatty acids.     

The utilization of a filamentous green alga (Cladophora glomerata (L) Kutzin) as a protein source in pelleted feeds for Sarotherodon (Tilapia) niloticus fingerlings

Duplicate groups of S. niloticus fingerlings were fed each of five different diets for 8 weeks. The diets contained 30% crude protein supplied by varying proportions of fishmeal and C. glomerata meal. The five diets were formulated to supply fishmeal protein: C. glomerata meal protein ratios of 30 : 0 (diet 1), 25 : 5 (diet 2), 20 : 10 (diet 3), 15 : 5 (diet 4) and 10 : 20 (diet 5) respectively. A sixth diet (diet 6) containing 25% crude protein supplied entirely by C. glomerata meal was also fed.

Diets 1 and 2 produced significantly the highest growth rates and best protein utilization. Highest values for protein digestibility were found in diets 2 and 3 (94.5 and 93.9% respectively) although the values were not significantly different from other treatments. Weight gain and protein utilization decreased as the level of algal protein increased in diets 2 to 6. Carcass analysis revealed a decrease in lipid and protein contents with increasing levels of algae in the diet. It is postulated that algal meals are viable partial dietary protein sources for tilapia.     

Comparison of amino acid profiles of feeds and fish as a quick method for selection of feed ingredients: a case study for Colossoma macropomum (Cuvier)

The amino acid profile of Colossoma macropomum was determined. Indispensable amino acid levels were similar to those reported in other fish species. Suitability of local, Costa Rican, ingredients as protein sources for C. macropomum was evaluated based on their protein content and indispensable amino acid profile. It was calculated that, in a standard diet (40% protein. 25% fish meal), blood meal, soya meal, poultry byproducts, meat and bone meal, and meat meal can substitute more than 80% of the fish meal. More than 40% of the fish meal can be substituted by shrimp meal, pigeon pea, cotton meal, peanut oil cake, cow pea, corn gluten and water hyacinth. As differences between amino acid profiles between fish species seem to be small, promising alternative ingredients for C. macropomum might be equally interesting for formulation of feeds for other species. Soya meal is the currently used ingredient with the highest potential to substitute fish meal completely. Further research is needed to determine if the use of alternative ingredients is limited by constraints such as decreased feed digestibility, presence of anti-nutritional factors, additional production and processing costs.     

Effects of substituting dietary fish oil with crude palm oil and palm fatty acid distillate on growth,muscle fatty acid composition and the activities of hepatic lipogenic enzymes in snakehead (Channa striatus,Bloch 1793) fingerling

Three diets were formulated to be iso‐nitrogenous (450 g kg^?1), iso‐lipidic (65 g kg^?1) and iso‐energetic (18.5 KJ g^?1), varying only in their lipid sources and designated as 100% fish oil (FO), 100% crude palm oil (CPO) and 100% palm fatty acid distillate (PFAD). Feed were hand fed to homogenous groups of 12 Channa striatus fingerlings (mean weight 3.5 ± 0.3 g) per tank in triplicate for 12 weeks, in a recirculation system. The growth performance and feed intake in the CPO and PFAD treatments were significantly (P<0.05) higher than those in the fish fed the control diet (FO), respectively, whereas the feed conversion ratio was better in PFAD than that in the other treatments respectively. The biological indices monitored (hepatosomatic index and viscerosomatic index) as well as carcass yield did not vary significantly among all the treatments respectively. The muscle fatty acid (FA) profile of fish was influenced by the composition of the diets fed, whereas no differences were recorded in the activities of the hepatic lipogenic enzymes monitored (fatty acid synthetase, citrate cleavage enzyme and malic enzyme). Whole‐body proximate composition analysis revealed that PFAD treatment, compared with others, contained significantly higher protein and ash, but lower lipid contents, although the muscle content of these nutrients was similar among all the treatments. Based on the results of this trial, CPO and PFAD could be used to partially substitute FO in the diet for C. striatus fingerling, to achieve good growth performance without any negative effects or compromising the muscle n‐3 FA composition (especially in the docosa hexaenoic acid and eicosa pentaenoic acid content).     

Efficient utilization of dietary lipids in Octopus vulgaris (Cuvier 1797) fed fresh and agglutinated moist diets based on aquaculture by‐products and low price trash species

The aim of this study was to evaluate growth, biochemical composition and dietary nutrients utilization in Octopus vulgaris fed on four diets based on bogue Boops boops, from different origin and in two presentations: fresh discarded bogue (aquaculture by‐product) (DB‐f), fresh wild bogue (low price trash species) (WB‐f), discarded bogue agglutinated moist diet (DB‐m) and wild bogue agglutinated moist diet (WB‐m). Diets based on DB showed higher lipid content (19–26% dw) than those based on WB (5–6% dw). Octopuses fed on DB‐based diets showed higher growth (1.5–1.9% day^?1) and higher protein efficiency ratio (0.64–0.69) than those fed on WB‐based diet (1.1–1.5% day^?1 and 0.36–0.37 respectively), which suggests good utilization of dietary lipids and also a possible protein sparing effect by lipids in O. vulgaris. Octopuses fed on diets presented fresh showed a higher growth (1.9–1.5% day^?1) and a higher feed efficiency (62–65%) than those fed on agglutinated diets (1.1–1.5% and 52–60% day^?1 respectively). Regarding fatty acids, the digestive gland clearly reflected dietary lipid and fatty acid profile, while muscle showed a more stable composition. Low dietary ARA content reflected in octopus tissues, especially in specimens fed on DB‐based diets, which did not seem to affect growth during the experimental period.     

Evaluation of soybean meal as alternative to fish meal in diet for juvenile Asian red‐tailed catfish (Hemibagrus wyckioides)

A feeding trial was conducted to determine the amount of soybean meal (SBM) that could replace fish meal (FM) without compromising growth and health of Asian red‐tailed catfish (Hemibagrus wyckioides). Five isonitrogenous and isoenergetic diets (S0, S15, S30, S45 and S60) were formulated with SBM to replace 0%, 15%, 30%, 45% and 60% of FM. The replacement level up to 30% improved daily growth coefficient, plasma adenosine monophosphate deaminase (AMPD) and alanine aminotransferase (ALT) activities and IgM content, and hepatic ALT, aspartate aminotransferase (AST) and glutathione reductase activities, whereas these were depressed by a further inclusion. The highest protein efficiency ratio and lowest feed conversion ratio were observed in fish fed the S15 diet. Replacement of FM with SBM generally decreased plasma insulin and insulin‐like growth factor 1 (IGF‐1) contents and hepatic catalase activity, whereas no significant differences were observed among fish fed the S0, S15 and S30 diets. In contrast, replacing FM with SBM generally increased blood urea nitrogen content, and that was higher in fish fed the S60 diet compared to fish fed the S0 diet. The highest growth hormone (GH) and glutamate dehydrogenase (GDH) activities were observed in fish fed the S30 diet. Fish fed the S30 and S45 diets exhibited the highest hepatic AMPD, GDH, IGF‐1 and target of rapamycin mRNA levels and muscle AMPD and GDH mRNA levels, whereas those were lowest in fish fed the S60 diet. These results indicate that under the reported conditions SBM may be included in the diet up to 222 g/kg as a substitute for FM, replacing about 30% of FM protein in juvenile H. wyckioides.