Enhancing tilapia robustness: Moringa essential oil improves growth, gut morphology, innate immunity, antioxidant capacity, and ammonia tolerance in Nile tilapia

This study investigated Moringa oleifera essential oil (MEO) as a functional feed additive for Nile tilapia ( Oreochromis niloticus ), focusing on ammonia stress mitigation. A 56-day trial allocated 300 fish into five groups (0 %, 0.5 %, 1 %, 1.5 %, or 2 % MEO supplementation). Results demonstrated that MEO significantly enhanced growth performance, increasing final body weight, weight gain, specific growth rate, feed intake, feed efficiency, and protein efficiency ratio, while reducing the feed conversion ratio (FCR). Optimal inclusion levels were 1.3–1.4 % for growth. Furthermore, histological examination demonstrated that MEO supplementation significantly improved intestinal morphology, characterized by increased villus height, enhanced goblet cell density, and greater villous branching complexity compared to control groups. The MEO-supplemented groups exhibited significantly higher immun e response , evidenced by elevated innate immune responses (lysozyme activity, IgM levels, phagocytosis). Concurrently, antioxidant capacity improved through upregulated activities of superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase (CAT), elevated total serum protein, coupled with a reduction in malondialdehyde (MDA). Furthermore , the oligopeptide transporter ( PepT1 ), M ucin ( Muc ), Insulin like growth factor ( IGF-1 ), Growth hormone receptor ( GHR1 ), G lutathione peroxidase ( GPx ), Catalase ( CAT ), L ysozyme ( LYZ ), Complement ( C3 ) genes expression significantly increased in MEO supplemented groups. Following ammonia challenge, Moringa oleifera essential oil (MEO) supplementation significantly enhanced ammonia tolerance in Nile tilapia ( Oreochromis niloticus ), as evidenced by prolonged LT50 values, while simultaneously suppressing stress responses through reduced plasma cortisol and glucose levels. Collectively, our findings indicate that dietary MEO inclusion improves growth performance while positively modulating physiological status through three key mechanisms: enhanced immune function, strengthened antioxidant defenses, and effective prevention of ammonia stress-induced physiological disruptions. This positions MEO as a multifunctional feed additive for sustainable tilapia aquaculture under challenging environmental conditions. • MEO significantly increased final body weight, weight gain, and feed efficiency. • MEO boosted key immune indicators, including immunoglobulin levels, phagocytic activity. • MEO raised antioxidant enzyme activity (SOD, GPx, CAT) and reduced oxidative stress (MDA). • MEO upregulated genes involved in growth (IGF-1, GHR1), immunity (LYZ, Complement C3), nutrient absorption (PepT1), and gut barrier function (Muc). • MEO supplementation prolonged LT50 values during ammonia challenge, demonstrating enhanced ammonia tolerance.