Total replacement of fishmeal by alternative protein sources in Clarias gariepinus (Burchell, 1822) feeds

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.