Impacts of coffee parchment on growth, immunity, and gut microbiota of Nile tilapia (Oreochromis niloticus) in biofloc system

Abstract

This study aimed to evaluate the potential of coffee parchment (CP), an underutilized agro-industrial by-product, as a functional feed additive for Nile tilapia (Oreochromis niloticus) reared in a biofloc system. Coffee parchment is rich in bioactive compounds and may offer sustainable benefits to aquaculture. To assess its effects, 300 fingerlings (average weight 18.60 ± 0.09 g) were randomly allocated to five groups and fed diets containing 0, 5, 10, 20, and 40 g kg−1 of CP for eight weeks. Growth performance, immune responses, the expression of growth-, immunity-, and antioxidant-related genes, and gut microbiota composition were examined. The results showed that CP supplementation significantly improved growth and immunological parameters, with the best overall effects observed in the CP5 group. CP5 led to significant upregulation of ghrelin, galanin, EF-1α, NPY-α, IL-1β, TNF-α, NFkB, MHC II-α, Hsp70, GPX, and Nrf2 genes. Microbiota analysis revealed 69 shared ASVs across treatments, with CP supplementation causing clear shifts in bacterial composition. CP5 reduced Proteobacteria abundance and microbial richness and evenness, suggesting selective modulation of gut communities. Polynomial regression analysis based on growth performance data estimated an optimal CP dosage range of 15.06–19.86 g kg−1. In conclusion, coffee parchment is a promising functional feed additive that enhances growth, immunity, gene expression, and gut microbiota modulation in Nile tilapia reared in biofloc systems. These findings support its application in sustainable aquaculture; however, further validation under commercial farming conditions is recommended.