ORCID

Abstract

As global aquaculture expands, sustainable alternative feed ingredients are needed to reduce reliance on fishmeal (FM) and conventional plant proteins. Herein, this study evaluated defatted black soldier fly (BSF; Hermetia illucens) larvae meal as a replacement mainly for soybean meal (SBM) and soy protein concentrate (SPC) in juvenile mirror carp diets. Fish (initial weight: 7.28 ± 0.09 g) were reared in a recirculating aquaculture system and fed for 8 weeks on either a control diet or diets containing 20% (BSF20) or 40% (BSF40) BSF meal. After the trial, growth performance was significantly improved in BSF-fed groups, with higher final weight, weight gain, specific growth rate and a better feed conversion ratio compared with the control. Orthogonal polynomial contrasts indicated predominantly linear responses in growth and feed utilisation parameters. Histological analysis showed significantly enhanced intestinal morphology in BSF-fed groups, including increased mucosal fold length (MFL), microvilli length (MVL) and intraepithelial lymphocyte (IEL) density. At the molecular level, il10 and slc6a18 expression were significantly upregulated in the anterior intestine (AI) and posterior intestine (PI), respectively, of BSF-fed fish. The PI microbiota profiling via 16S rRNA gene metabarcoding showed that BSF inclusion promoted several beneficial microbial shifts. While the dominant phyla were Proteobacteria, Fusobacteria and Firmicutes, fish fed the BSF40 diet exhibited a higher relative abundance of Firmicutes and a reduced relative abundance of several potentially pathogenic phyla. The relative abundance of beneficial genera, including Bacillus and Enterococcus, increased significantly, whereas the relative abundance of potentially pathogenic genera such as Mycobacterium, Staphylococcus and Enterobacter was reduced by BSF meal. Overall, BSF meal represents a nutritionally viable and functional protein source that improves growth performance and intestinal health and supports sustainable aquafeed development in juvenile mirror carp.

Publication Date

2026-06-29

Publication Title

Aquaculture Research

ISSN

1355-557X

Acceptance Date

2026-05-29

Deposit Date

2026-08-26

Funding

The UK Foreign, Commonwealth & Development Office (FCDO) for funding this research through the Commonwealth Scholarship Commission (CSC) Grant Number: ZMCS-2022-676

Keywords

aquaculture, carp, gut health, Hermetia illucens, insect, sustainable

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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