# Evaluation of Hermetia illucens Larvae Oil as a Dietary Substitute for Fish and Vegetable Oils in African Catfish Hybrid (Clarias gariepinus × Heterobranchus longifilis)

## TL;DR

This study shows that black soldier fly larvae oil can replace fish and vegetable oils in the diets of African catfish hybrids without harming their growth.

## Contribution

The study demonstrates that black soldier fly larvae oil can serve as a sustainable alternative to fish and vegetable oils in aquafeeds.

## Key findings

- Fish growth and nutrient utilization were similar across diets with different levels of black soldier fly larvae oil.
- Replacing fish oil with black soldier fly larvae oil altered fatty acid profiles and gene expression in the liver.
- Black soldier fly larvae oil inclusion showed potential benefits for sustainable aquaculture feed development.

## Abstract

Alternative sources of dietary fish oil (FO) are necessary for the growth of the aquaculture industry. This study investigated the potential benefits of black soldier fly larvae oil (BSFLO) as a feed ingredient in the diets of African catfish hybrids (Clarias gariepinus × Heterobranchus longifilis). Three isonitrogenous and isolipidic diets—a control diet (CTR) containing a FO and rapeseed oil (RO) mixture (50:50), IO50 containing BSFLO replacing 50% of FO and RO mixture and IO100 containing 100% BSFLO—were formulated. A total of 900 fish juveniles (average initial weight: 29.1 ± 1.69 g) were randomly distributed into three dietary groups, each replicated three times and reared in a recirculation aquaculture system for 7 weeks. Results showed similar fish growth between dietary groups (final body weight: CTR, 155.27 ± 4.45 g; IO50, 162.47 ± 0.19 g; IO100, 160.87 ± 3.78 g). In addition, nutrient utilisation parameters and whole-body crude protein, lipid and ash content were similar between groups. The levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the whole body decreased while that of arachidonic acid (ARA) increased with IO inclusion. Similar trends in ARA and EPA levels were observed in the liver, the DHA/EPA ratio being highest in fish fed IO100 diet. The hepatic expression of pparα (peroxisome proliferators activated receptor alpha), hnf4α (hepatocyte nuclear factor 4α) and hadh (hydroxyacyl-CoA dehydrogenase) followed quadratic trends being lowest in fish fed IO50 and highest in fish fed IO100. The lpl (lipoprotein lipase, LIPA) gene was significantly upregulated in fish fed IO100. The liver malondialdehyde (MDA) content was lowest in fish fed IO50. In addition, plasma myeloperoxidase (MPO) activity linearly increased with IO inclusion. These results demonstrate that potential benefits are achieved when BSFLO is supplemented in diets of African catfish hybrids, contributing to the development of sustainable alternatives to fish and vegetable oils (VOs) in aquafeeds.