Physiological Response of Grower African Catfish to Dietary Black Soldier Fly and Mealworm Meal

SIMPLE SUMMARY: Sustainability and profitability of African catfish farming depends on a sustainable and cost-effective supply of feed. Fish meal is still used as the main dietary protein source in the practical diet of fish. However, the supply shortage and high cost are the limiting factors. Insects may represent a promising candidate for fish feeding due to their low footprint production and nutritionally relevant properties. This study revealed that replacement of fish meal with black soldier fly did not negatively affect the production performance and metabolic response of African catfish growers. On the other hand, replacement with yellow mealworm may lead to the fish’s growth reduction and health problems. ABSTRACT: A six-week experiment was carried out to test the effects of total (100%) and partial (50%) replacement of fish meal in the diet of African catfish growers with black soldier fly (B) meal, yellow mealworm (M) meal, and a 1:1 combination of both (BM) on the production and health of fish. A total of 420 fish with an average initial body weight of 200 ± 0.5 g were randomly distributed in triplicate to seven diet groups (C, B50, B100, M50, M100, BM50, and BM100, respectively). The growth performance and feed utilization of fish fed with partial or total replacement levels of FM with B were not significantly affected (p > 0.05) during the 6 weeks of feeding. In contrast, significant differences were observed between the groups fed with a diet where FM was totally replaced with M meal and the control in terms of final body weight, specific growth rate, feed conversion ratio, protein efficiency ratio, and protein productive value. Among the blood plasma biochemistry parameters, total cholesterol exhibited a significant difference (p = 0.007) between the M treatments and the control diet. The fatty acid profile of the liver was changed with respect to the long-chain polyunsaturated fatty acid content in all experimental groups. Parallel with this, the upregulation of elovl5 and fas genes in liver was found in all experimental groups compared to the control. Overall, this study shows that fish meal cannot be substituted with yellow mealworm meal in the practical diet of African catfish without compromising the growth, health and feed utilization parameters.