Combined Substitution of Fishmeal and Fish Oil With Black Soldier Fly Larval Meal and Corn Oil: Effects on Growth, Hematology, Hematobiochemical, Amino and Fatty Acid Composition, and Fillet Nutritional Quality of Hybrid African Catfish Clarias gariepinus × Heterobranchus longifilis

This study aimed to evaluate growth performance, amino acid and fatty acid composition of fillets, and blood biochemistry of hybrid catfish (Heteroclarias) cultured on Black Soldier Fly (BSF), Hermetia illucens larval-based diets. The experiment was conducted in a recirculating system, circular poly tanks (350 L), in a completely randomized design. Four isonitrogenous (400 g kg−1 crude protein) and isolipidic (140 g kg−1 crude fat) diets were formulated in which fishmeal (400 g kg−1) was replaced at 0%, 25%, 50%, and 75% with defatted BSF larval meal and fish oil was completely replaced with corn oil in the test diets. 180 hybrid African catfish (12 weeks post-hatching) with an initial body weight of 200 ± 25 g were randomly distributed in the 12 experimental tanks (15 fish per tank, 45 fish per treatment) and were hand-fed at 3% body weight for 8 weeks. The findings showed that replacing 50% of fishmeal with BSF meal resulted in the highest growth performance (final weight, weight gain, specific growth rate [SGR], thermal growth coefficient [TGC]). However, at 75% level, growth performance and nutrient utilization (FCR, PER) significantly decline (p <0.05). The dietary modification had no significant impact (p >0.05) on organosomatic indices, proximate composition, amino acid profile, deposition, or retention of arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and sum n-3 polyunsaturated fatty acids (PUFA) in fish fillets. There were no significant differences in the hematological parameters (p >0.05) across all treatments. Except for a reduction in globulin and cholesterol levels, all the plasma metabolites, including alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, remained stable (p >0.05). Overall, the findings of this study suggest that BSF larval meal may partially replace dietary fishmeal up to 50% (200 g kg−1), and corn oil may completely replace fish oil in a practical diet for hybrid African catfish without exerting adverse impacts on growth, feed conversion efficiency, fillet quality, health status, and physiological well-being.