To completely replace the fish meal by a mixture of earthworm and maggot meals, experimental diets were tested during 42 days on Clarias gariepinus fingerlings. Five isoproteic and isoenergetic diets (40 % crude protein and 17.9 ± 0.3 kJ g⁻¹) including the control diet (D1) based on fish meal, were formulated. All these diets satisfied the essential amino acids requirements of C. gariepinus fingerlings. These diets were tested on triplicate groups of 50 fishes (initial body weight: 3 ± 0.1 g) bred in tank (0.5 m³). The approximate ratios 2:5; 1:4; 1:12 and 0:1 between the earthworm meal and the maggot meal were used, respectively, to formulate four diets D2, D3, D4 and D5 without fish meal. After the feeding period, significant differences (P < 0.05) were observed on growth, feed utilization between control diet (D1) and test diets (D2–D5). Fish fed earthworm- and maggot-based diets were grown better than those fed the control diet. Survival and feed utilization were not significantly affected by the ratio between earthworm meal and maggot meal in the test diets. Lipid content was higher in carcass and fillet of fishes fed earthworm- and maggot meals-based diets than that of those fed fish meal-based diet. This study indicates that when the ratio 2:5 between the earthworm meal and the maggot meal is used to entirely replace fish meal and the ratio lysine/arginine of the diet is inferior to 1, the growth performances and feed utilization of Clarias gariepinus fingerlings are improved.

Amino Acids Composition of Maggot, Earthworm, Termite and Chicken Viscera Meals Used as Proteins Sources in Fish Feeding

Alternative sources to fishmeal are increasingly being explored in the formulation of aquaculture feed in order to reduce pressure on fishery resources. To this end, in the total replacement of fishmeal, one hundred and fifty Clarias gariepinus fingerlings with an initial weight of 0.5 ± 0.01 g were fed five isoprotein and isoenergetic experimental diets (41, 9 ± 0.6% and 17.6 ± 0.5 kJ/g). Based on the essential amino acid profile, Azolla filiculoides, chicken viscera, maggot meal and soil worms were used in a mixture to replace fish meal entirely in the experimental diets (D2 to D5). Fishmeal was used in the control diet (D1) with an incorporation rate of 46%. All these diets, which met the essential amino acid requirements of C. gariepinus, were tested randomly in three replicates on fingerlings reared in aquariums containing 150 L of water each. At the end of the experiment, percentage weight gain (PWG) and final body weight (FBW) were not significantly affected by the different levels of mixing of alternative protein sources. Growth performance in the experimental diets (D2 to D5) was significantly different from D1 (p < 0.05). The feed conversion ratios (FCR) in the test diets were lower and different from the control diet (p < 0.05) significantly, except the diet D2 with an FCR = 1.06. These results showed that growth performance and feed utilization are mainly affected by the essential amino acid content of diets containing alternative protein sources. Anti-nutritional factors present in the ingredients would certainly limit the bioavailability of amino acids. This study showed that methionine, histidine and the lysine/arginine ratios are decisive in improving growth performance and feed utilization in C. gariepinus farming.

The captive breeding of the Silver catfish Schilbe intermedius was envisaged to promote the aquaculture and to reduce the overfishing of this endangered species. S. intermedius fingerlings were fed various dietary protein levels to investigate their growth performance, feed utilization and carcass proximate composition. Fish meal and casein were the sources of protein used in the study. Six isocaloric experimental diets containing 25%~60% crud protein (CP) diet have been fed to three-replicate six groups of forty (40) fishes (mean weight: 1.640 ± 0.015 g) for 8 weeks. Both percent weight gain and feed efficiency ratio significantly increased with increasing dietary protein levels up to 45%, while there were no significant differences for protein levels from 45 to 60%. Growth performances and nutrient utilization parameters of fingerlings fed different diets varied significantly (P < 0.05) and the highest growth performance and nutrient utilization were obtained with fish fed on a 45% CP diet. The second order polynomial regression between dietary protein and specific growth rate (SGR) indicated that protein requirements of S. intermedius fingerlings ranged from 42.5 to 53% of diet. The highest protein content of the fish carcasses was found in fish fed 45% dietary protein and there was not significantly different (P > 0.05) with that of fish fed 60% dietary protein. Lipid content increased with increasing dietary protein levels. The dry matter and protein content of the initial sample were significantly higher (P > 0.05) than the values after feeding the fish with experimental diets.

Growth Performance of Clarias gariepinus (Burchell, 1822) fed with Local Feed without Fish Meal