Fermented fish meal derived from barramundi by-product enhances growth, immunity, and gut microbiota in white shrimp Penaeus vannamei

This study investigated the effects of barramundi, Lates calcarifer, by-product fish meals on the growth, immunity, and gut microbiota of white shrimp, Penaeus vannamei. Three variants were assessed: untreated fish meal (BFM), enzymatically hydrolyzed fish meal (EBFM), and fermented fish meal (FBFM), alongside a commercial fish meal control. Compared to commercial fish meal, barramundi by-product meals exhibited lower crude protein but higher lipid and ash contents. Fermentation with Lactobacillus plantarum 7–40 notably increased methionine levels in FBFM. Shrimp fed diets containing EBFM or FBFM showed significantly greater weight gain, feed efficiency, and biomass production, with FBFM yielding the most pronounced improvements. FBFM supplementation also enhanced immune parameters, including phenoloxidase, respiratory burst, superoxide dismutase, lysozyme, and phagocytic activities, alongside upregulation of immune-related genes. Post-challenge survival against Vibrio alginolyticus was highest in the FBFM group. Gut microbiota analysis revealed reduced Vibrio abundance and increased beneficial genera (e.g., Enterococcus, Rubritalea) in FBFM-fed shrimp. Principal component analysis indicated distinct microbial profiles among treatments. These results highlight FBFM as a viable alternative protein source that improves shrimp growth, immunity, gut health, and disease resistance, supporting sustainable aquafeed development within a circular economy framework.