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The effects of replacing high percentages (50%, 75% or 100%) of dietary protein from fish meal with soy protein concentrate on growth, diet utilization, and carcass composition of the African catfish, Clarias gariepinus, was evaluated. Supplemental methionine was added to the diet formulation in which soy protein concentrate replaced 100% of fish meal protein. Diets were formulated (420 g crude protein/kg and 17.5 kJ gross energy/g dry diet) and fed to catfish fingerlings (13.1±0.5 g) to apparent satiation twice daily for 70 days. Replacement of 50% and 75% of fish meal protein with soy protein concentrate did not affect growth, feed utilization or carcass composition, which were similar (P > 0.05) to those fed with the control diet. At 100% replacement, growth and feed utilization were depressed and slightly inferior hematological characteristics were observed, compared with the other treatments. Liver histology of catfish fed any of the diets showed no alternations. Results indicate that 75% of...

Artificial spawning was induced in female African giant catfish, Heterobranchus bidorsalis by single intramuscular hormone injections of carp pituitary suspensions (CPS) at 4 mg/kg body weight (bw), 1.5 ml of homoplastic pituitary suspension (HPS) per fish or human chorionic gonadotropin (HCG) at 2000 IU/kg bw, over 3 months of rainy season (June to August) in Nigeria. At ambient temperature (27±1 °C), ovulation occurred within 14–18 h post injection. Egg hydration gave 16–20% increase in egg diameter. Hatching rates were high (>84%) and similar for all hormone-treated fish (P>0.05). The percentage normal larvae hatched ranged from 81.6% to 86%. They were reared in 500-l circular tanks and fed initially on zooplankton, followed by brine shrimp nauplii and finally weaned onto commercial fish fry diet. During the larval rearing trials for 30 days, survival rates >82% were achieved. Although the four hormones tested were effective inducers, the use of HPS would save operational costs in fish hatchery management in African countries.

Apparent digestibility coefficient (ADC) values for mechanically extracted meal derived from roquette (Eruca sativa) seeds were obtained. The digestibility of dry matter (DM), protein and energy was measured using an inert marker in the diets and by faeces collection using the dissection method. Soybean meal and roquette meal had similar ADC values for protein and energy. Roquette seed meal was thereafter evaluated as a protein source in diets (400-g crude protein, 120-g crude lipid and 18.00 MJ gross energy kg-1 DM) fed to African catfish, Clarias gariepinus, fingerlings (10.4±0.4 g) to apparent satiation twice daily for 70 days. The test diets contained roquette seed meal as replacement for soybean meal protein in a control diet, providing 20%, 40% or 60% of the total protein. Catfish mortality was low (

This study was undertaken to determine the replacement value of Cassia fistula seed meal (CFM) for soybean meal (SBM) in practical diets of Oreochromis niloticus fingerlings. Five practical diets (350 g kg−1 crude protein) containing 0 g kg−1 (control), 170 g kg−1 (diet II), 340 g kg−1 (diet III), 509 g kg−1 (diet IV) and 670 g kg−1 (diet V) substitution levels of CFM for SBM were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 10.22 ± 0.03 g) for 70 days. Fish mortality increased linearly with increase in inclusion levels of CFM in the diet. Growth and diet utilization efficiency were depressed in fish fed diets containing CFM at varying inclusion levels. Feed conversion ratio, specific growth rate and protein efficiency ratio of O. niloticus fed on diet containing 170 g kg−1 substitution level of CFM were similar (P > 0.05) to the control diet. Digestibility of the different diets decreased with increase in inclusion levels of CFM. Fish fed diet containing 670 g kg−1 CFM had significantly lower carcass protein. However, no significant differences were observed in carcass protein and lipid contents between fish fed the control diets and diet containing 170 g kg−1 CFM. The most efficient diet in terms of cost per unit weight gain of fish was obtained in 170 g kg−1 CFM dietary substitution.

Two aquatic plants: water fern, Azolla africana and duckweed, Spirodela polyrrhiza were evaluated as feedstuffs in production diets for Nile tilapia, Oreochromis niloticus fingerlings. Eleven diets (30% crude protein) containing fish meal protein substituted at a rate of 5, 10, 20, 30, and 100% for either of the plant ingredients were formulated. A diet without any of the plant ingredients served as the control. Nile tilapia fed diets containing duckweed showed superior growth performance. There were no significant differences (P > 0.05) in growth responses of fish fed either 10% duckweed and 5% water fern dietary inclusion or the control diet. There was a growth depression in fish with increased dietary inclusion of both plants. The most cost-efficient diet was obtained in a diet with 30% duckweed dietary inclusion. Results of this study indicated that duckweed and water fern could be substituted for fish meal protein up to 10% and 5%, respectively, in low-cost diets for Nile tilapia without com...

Mature winged bean ( Psophocarpus tetragonolobus ) (cultivar Tpt26) seeds were roasted or autoclaved and their meals evaluated as a dietary protein source for the African catfish. Five dry practical diets (400 g protein/kg and 17.5 kJ gross energy/g dry diet) containing menhaden fish meal or each of the heat-processed winged bean meals as partial replacement (80%), (with or without 5 g dl -methionine/kg diet supplementation) for menhaden fish meal, were prepared and fed to triplicate groups of catfish fingerlings (5.8±1.2 g) to satiation for 70 days. No mortality occurred throughout the study and satisfactory diet acceptance was observed when the heat-processed winged bean meals replaced menhaden fish meal. Differences were found in weight gain, specific growth rate, feed and protein efficiency ratios, but were not significant ( P >0.05). Digestibility of crude protein and gross energy content of the diets were high (>85%) and comparable to that of menhaden fish meal. Carcass composition of catfish did not vary significantly ( P >0.05) between diet treatments. Results indicate that both autoclaved and roasted winged bean meals were acceptable as protein sources and can replace 80% of menhaden fish meal in catfish diets.

Induced breeding trials of two clariid catfishes, Clarias gariepinus and Heterobranchus bidorsalis, were conducted using five doses (2, 4, 6, 8 or 10 mg/kg) of acetone-dried tilapia pituitary (ADTP) extracts. Oocyte maturation and ovulation were induced in female catfishes by single intramuscular injection of 6–10 mgkg ADTP; optimum results were obtained with 8 mgkg in both catfishes. At ambient temperature (27 ± 1 C). ovulation occurred within 14–18 h post-injection resulting in 16–20% increase in egg diameter. Fertilization and hatching percentages increased (P < 0.05) with increases in hormone dosage. Survival of fry fed a mixed zooplankton diet was high (ranging from 79% to 85%) after 30 d of rearing.

Macadamia presscake, the by-product from oil extraction process of low-grade kernels of macadamia nuts, was evaluated as a dietary protein supplement for tilapia, Oreochromis niloticus (L.), reared in outdoor concrete cisterns. Five isoproteic diets (28% crude protein) were fed to tilapia for 100 days. The diets comprised a control, which contained full-fat soybean as the protein source, and four test diets in which the full-fat soybean meal was progressively substituted (10%, 20%, 50% or 100%) with macadamia presscake. Final weight, daily weight gain, specific growth rate and apparent protein digestibility were significantly different (P 0.05). Body protein deposition was not affected by the inclusion level of mac-adamia presscake in the diet. Results showed that macadamia presscake was suitable as a dietary protein supplement for tilapia when incorporated up to 50% replacement for soybean protein. The nutrient content of full-fat soybean meal is apparently similar to that of macadamia presscake but the quantity of macadamia presscake in fish feeds may be limited due to the less-than-optimal amino acid balance in macadamia presscake-protein.

Fermented fish silage was prepared from whole mixed-sex tilapia (Oreochromis niloticus), 15% molasses and 5% Lactobacillus plantarum starter culture and used as protein source in tilapia diets. Four alternative binders (carboxymethyl cellulose, corn starch, guar gum or wheat gluten) were incorporated in diets at 3% and their effects on water stability and nutrient leaching were determined. Water stability of the pellets showed that high physical stability of the pellets was maintained regardless of the binder used, and losses of total nitrogen were low (< 3%) on a per gram diet recovered basis. All-male O. niloticus fingerlings (mean weight, 48·9 g) were fed the appropriate diets at a rate of 5% of body weight per day, twice daily, for 30 days in a recirculated water system with water temperature maintained at 27°C. Apparent digestibility coefficients for dry matter, nitrogen or lipid in the diets were high and similar when carboxymethyl cellulose, corn starch or wheat gluten was used as the binder; but were reduced (P < 0·05) with guar gum.

Resume Fagbenro O., K. Jauncey, G. Haylor. Aquat. Living Resour., 1994, 7, 79-85. Dry diets containing varying levels of dried fermented fish silage and soybean meal blend (FS: SBM) as replacement for 25,50 or 75 % of fish meal protein were fed to juvenile Oreochromis niloticus (8.210.1 g) and Clarias gariepinus (10.8k0.3 g) at 5 % body weight per day for 70 days. Diets containing CO-dried FS: SBM supported weight gains and growth rates similar to those in the control treatment without significant differences @>0.05). Feed conversion, protein efficiency ratio and protein productive values followed a similar trend with growth performance values. Apparent protein digestibility decreased in both fish species with increasing dietary level of CO-dried FS: SBM. Carcass composition of experimental fish were not affected by the diets and morphological defects were not observed. Results indicate that CO-dried FS: SBM can partially replace fish meal protein as well as establish the potential of utilizing wastehndersized tilapias as a protein feedstuff in dry aquaculture diets.

Clarias isheriensis Sydenham fingerlings (60·42 ± 1·13g) were fed for 180 days with pelleted diets in which maize was progressively replaced with graded levels (0, 15,30,45%) of cocoa-pod husk meal (CPHM). There was a decline in growth rate with increase in dietary CPHM level, though this was not significantly different (P 0·05). Fish mortality was low (< 2%) in all dietary treatments tested. Lack of significant difference in growth performance and nutrient utilization indicated that CPHM could be incorporated into low-cost diets for C. isheriensis up to the 30% level. In a second experiment, three feeding regimes of 15% CPHM diet were tested with C. isheriensis fingerlings (60·81 ± 1·87g) over 180 days and results showed no significant (P > 0·05) differences among the feeding regimes tested, with regards to growth, feed conversion and fish yield. This suggests that the growth of C. isheriensis from fingerling to adult size (≥ 200g) can be satisfied in one single feeding equivalent to 3% body weight per day.

Defatted cocoa cake, a by-product of the cocoa fermentation process, was evaluated as a direct feed in the monosex culture of Tilapia guineensis (Dumeril) stocked at 10 000/ha in 160-m 2 earthen ponds. Experimental yield trials were compared with two types of controls: a locally manufactured fish diet and an unmanaged system. A completely random design was used with three treatments replicated three times and lasting 120 days. Survival of the fish ranged from 90.21 to 93.13%. At harvest, average net yields were 2310.00, 1707.50 and 1133.13 kg/ha from the fish diet treatment, cocoa cake treatment and unmanaged system, respectively. Feed conversion values (based on dry matter inputs) averaged 5.12 and 2.30 for the fish fed the cocoa cake and fish diet, respectively. Analysis of the stomach contents of fish from the experimental pond showed that cocoa cake was utilized directly as feed.