Immunomodulatory, antioxidant, and growth-promoting properties of Avicennia marina leaf extract on Nile tilapia

This study evaluated the effects of Avicennia marina leaf aqueous extract on Nile tilapia performance. Fish (5.15 g, n = 675) were fed diets containing 0, 100, 200, 300, and 400 mg/kg extract for 60 days. Fish fed 200-300 mg/kg diets showed better growth status (P < 0.05), along with improved feed utilization. Digestive enzyme levels (amylase, lipase, protease) were better, and intestinal histomorphology was optimized, particularly at 200-300 mg/kg. Biochemical assessment of the serum indicated increased levels of total protein, albumin, and globulin, with reduced glucose, cholesterol, and cortisol in fish receiving 200-400 mg/kg. Hepatic antioxidants (SOD, CAT, GSH-Px) increased, while malondialdehyde (MDA) decreased. Immune responses (lysozyme, NBT reduction, Streptococcus agalactiae inhibition) were enhanced, and gene expression showed upregulated IGF-1, SOD, CAT, and GSH-Px with downregulated IL-1β and TNF-1α in the 200-400 mg/kg groups. Dietary A. marina extract at 200-300 mg/kg enhanced growth, digestive efficiency, antioxidant status, immune functions, and gene expression in Oreochromis niloticus, suggesting its promise as a natural feed additive in aquaculture.