Black Soldier Fly Larvae as a Fishmeal Alternative: Effects on Growth, Muscle Quality, Antioxidant Status and Gut Microbiota of Juvenile Pangasius

Abstract

To evaluate the economic and ecological potential of black soldier fly larvae (BSFL) slurry as a fishmeal alternative, 270 juvenile Pangasius (initial body weight: 7.20 ± 0.07 g) were acclimated for two weeks and randomly allocated to three dietary treatments (T0, T1, T2), with three biological replicates per treatment. The feeding trial lasted six weeks (42 days). Fish in T0 were fed the basal diet, while T1 and T2 diets replaced 50% and 100% of fishmeal with BSFL on an isonitrogenous basis, respectively. At trial termination, whole-body proximate composition, muscle texture, and intestinal microbiota were analyzed. BSFL inclusion at 50–100% fishmeal replacement did not compromise growth performance. Moisture and ash content did not differ among treatments (p > 0.05), whereas BSFL supplementation significantly altered muscle texture, reducing hardness and resilience while increasing springiness, chewiness, cohesiveness, and adhesiveness. Both 50% and 100% BSFL replacement enhanced hepatic antioxidant capacity, evidenced by significantly higher superoxide dismutase (SOD) activity (p < 0.05). BSFL also modulated intestinal microbiota and enhanced community evenness, though without significant intergroup differences in bacterial abundance (p > 0.05). This study demonstrated that BSFL could replace 50–100% of fishmeal in diets for juvenile Pangasius, maintaining growth performance while modifying nutritional profiles, muscle texture, hepatic antioxidant status, and intestinal microbiota. Nevertheless, 100% fishmeal replacement triggered distinct shifts in intestinal microbial composition despite satisfactory growth, and the 50% substitution level was, therefore, recommended as a safe proportion for practical aquafeeds.