Black soldier fly larvae oil as a potential nutraceutical ingredient in diets for hybrid catfish Ictalurus punctatus × I. furcatus juveniles

The present study evaluated the potential of black soldier fly larvae (BSFL) oil as a substitute for catfish oil in diets of hybrid catfish juveniles. Nine hundred hybrid catfish juveniles (~17.4 g initial weight) were equally distributed in 30, 110-L aquaria, operating as a recirculating system. Experimental diets were formulated to be isonitrogenous (36 % of crude protein), isolipidic (8 % of crude lipid), and isocaloric (20.45 MJ/kg of digestible energy) containing BSFL oil as a substitute for catfish oil at 0, 25 %, 50 %, 75 % and 100 % replacement levels. Fish were fed to apparent satiation twice a day for 60 days. At the end of the feeding trial, the fish had ~361 % weight gain. BSFL oil inclusion significantly affected weight gain, feed efficiency, and viscerosomatic index, with a negative impact on production performance observed at inclusion levels exceeding 50 %. Based on broken line regression analysis, the maximum replacement of catfish oil with BSFL oil ranged between 54 % and 62 %. Dietary treatment did not produce any observable differences in the alpha and beta diversity metrics of the intestinal microbiota, consequently, no significant LEfSe results were found. Similarly, BSFL oil did not lead to differences in moisture, protein, lipid, or ash of whole-body tissues. Protein conversion efficiency was significantly affected by BSFL oil inclusion, with a maximum replacement of 25 %. Fatty acid composition of fish fillet demonstrated differences among dietary treatments, mainly due to reductions in eicosapentaenoic and docosahexaenoic acids. Further, dietary treatments did not negatively impact survival in response to Aeromonas hydrophila challenge. These data suggest BSFL oil can be included at 1.95 % (50 % catfish oil replacement) in hybrid catfish feeds without significantly impairing production performance. Keywords: Black soldier fly oil, Catfish oil, Disease resistance, Growth performance, Hybrid catfish, Insect oil, Lipids source. • BSFL oil can replace 50 % of lipids in hybrid catfish diets without affecting production performance • Dietary BSFL oil did not adversely affect hematological and immune parameters • The whole-body composition was not affected by dietary BSFL oil inclusion