Effects of Dietary Supplementation with Black Soldier Fly Larvae (Hermetia illucens) Frass on Common Carp (Cyprinus carpio)

Frass is the by-product of the larval meal industry and consists of leftover feed materials, exoskeleton shedding, and larval excrement of black soldier fly larvae (BSFL). To assess the impact of dietary frass (BSFLF) on the growth, feed consumption, biochemical indices, whole-body proximate composition, serum biochemical indices, and fatty acid composition (hepatopancreas) of common carp (<i>Cyprinus carpio</i>), an 8-week study was carried out. Juveniles were fed diets with different inclusion of BSFLF levels (0%, 10%, and 20%) in a recirculating aquaculture system, with each diet randomly assigned to a triplicate group of 90 fish (10 fish per tank), with an initial weight of 119.35 ± 30.97 g stocked into 250 L tanks. The study found that increasing dietary frass led to increased growth rates, relative growth rate, weight gain, and protein efficiency ratios, and to decreased feed conversion ratios. Within both total phospholipid and triglyceride fatty acid compositions, the 20% dietary frass increased proportions of saturated and omega-3 fatty acids while decreased the oleic acid (C18:1n9) proportion. To sum up, the use of BSFLF, notably at a 20% inclusion level, as a source of dietary protein has the potential to significantly improve the overall productivity of common carp.