Abstract
Introduction The overuse of antibiotics in aquaculture has raised concerns, necessitating the exploration of sustainable alternatives. This study evaluated tea-derived additives as potential substitutes. Methods This study evaluated the effects of black tea powder (BTP) and black tea powder-probiotics mixed fermentation product (TPMFP) on Cherax quadricarinatus growth, antioxidant capacity, and gut microbiota. Cherax quadricarinatus were fed diets supplemented with BTP (1–6%) or TPMFP (2%) for 84 days. Results The addition of BTP (<2%) to the feed enhances the weight, carapace length, and muscle protein content of Cherax quadricarinatus , while higher doses (>3%) showed adverse effects. Moreover, the addition of BTP (1%-6%) can significantly reduce the muscle content of CHO, TG, and HDL (P<0.05). The TPMFP group exhibited the highest muscle protein content and significantly elevated hepatopancreatic SOD, GSH-PX, and AKP activities (P < 0.05), indicating improved antioxidant capacity. Gut microbiota analysis revealed dose-dependent shifts, with Proteobacteria dominating (>70%) and Aeromonas increasing with BTP levels. TPMFP significantly increased the α-diversity indices (richness and evenness) of the gut microbiota. The Mantel test confirmed the relationship between the antioxidant function of the microbial community, with Proteobacteria positively correlated with GSH-PX/SOD, while Fusobacteria and Tensionella negatively correlated with antioxidant enzyme activity. Discussion This study provides a foundation for using tea-derived additives as a sustainable alternative to antibiotics in aquaculture.In the future, metagenomic analysis of key metabolic pathways can be combined to optimize the mechanistic explanation of the application and efficacy of BTP and TPMFP.