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

## TL;DR

Adding black soldier fly larvae frass to common carp diets improves growth and productivity, especially at 20% inclusion.

## Contribution

Demonstrates that 20% black soldier fly larvae frass enhances common carp growth and feed efficiency.

## Key findings

- 20% frass inclusion significantly improved growth rates and protein efficiency ratios in common carp.
- Frass increased saturated and omega-3 fatty acids while decreasing oleic acid in fish lipids.
- Higher frass levels led to lower feed conversion ratios, indicating better feed utilization.

## Abstract

Finding alternative feed ingredients is crucial to minimizing reliance on limited traditional resources, despite rising global demand for fish feed. Black soldier fly larvae (BSFL) frass—the excrement and residual feed components from larvae farming—is considered a nutrient-rich, sustainable, and cost-effective ingredient for aquaculture. Our investigation evaluated the impact of black soldier fly larvae frass at inclusion levels of 10% and 20% on the growth performance and physiological development of common carp. Our results suggest that the dietary group incorporating 20% frass can significantly enhance the overall productivity of common carp compared to both the control and the 10% frass groups. In general, frass has the potential to promote the development of sustainable aquaculture diets.

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 (Cyprinus carpio), 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.