Black soldier fly (Hermetia illucens) larvae exoskeleton as a potential source of chitin in diets for juvenile channel catfish (Ictalurus punctatus).

This study investigated the effects of dietary supplementation of chitin from the exoskeleton (exuviae) of black soldier fly larvae (BSFL) and purified chitin (PC) from shrimp in diets for channel catfish juveniles. Five experimental diets were formulated to provide chitin at two inclusion levels (500 and 1000 mg kg^-1). A diet devoid of chitin was used as a control. The feeding trial was performed for 9 weeks with 1000 channel catfish juveniles (~ 1.8 g), randomly distributed into 25 experimental units (110 L; 40 fish aquarium^-1), in a recirculating aquaculture system. Data from production performance, whole-body proximate composition, whole-blood and plasma immunological responses, intestinal microbial community profiles, as well as susceptibility to Edwardsiella ictaluri challenge were evaluated. There was no impact on growth or health parameters of juvenile catfish; however, the BSFL500 diet resulted in a significantly lower viscerosomatic index. Fish-fed diets containing 1000 mg of chitin kg^-1, trended toward less rich intestinal bacterial communities compared to groups fed with other diets. Additionally, the BSFL groups had distinct bacterial community structures compared with the other treatments. After the feeding trial, the remaining fish were challenged with E. ictaluri immersion, and fish-fed BSFL1000 and PC500 demonstrated lower cumulative survival. These results fail to support the use of chitin as a feed supplement for improved fish growth or health parameters in juvenile catfish. However, shifts in the intestinal microbiota suggest a potential prebiotic role, warranting further research to better define the putative utility of chitin in catfish nutrition and health management.