E-64

Arsenic (As) residue is present predominantly in aquatic ecosystem and fishery products globally, which is critically hazardous to both fish and consumer health beyond its permissible limit. Therefore, finding effective ways to mitigate As toxicity has become a priority. Hence, Moringa oleifera (M. oleifera), a medicinal plant containing several pharmacological properties, was evaluated for reducing adverse effects of sub-lethal concentration of As (1/3rd of 96 h LC₅₀ = 6.75 mgL^-1) in Labeo rohita (Rahu). Briefly, healthy acclimatized individual of L. rohita were allotted into four aquariums and named as T₁, T₂, T₃ and T₄. Each group had three replicates (10 fish in each aquarium). T₁ group served as control, exposed with no As and fed with basal diet. T₂, T₃ and T₄ groups were exposed to As and treated with 0, 2 and 4 % M. oleifera leaf extract supplemented diet respectively, for 28 days. Fish exposed to As and fed a diet with 0 % M. oleifera leaf extract exhibited increased histological alterations, elevated levels of liver enzymes, cortisol, antioxidant status, and relative expression of the cytochrome P450 gene, while showing significant decreases in skin mucosal immune responses (lysozyme, protease, antiprotease, and peroxidase activities). However, As exposed fish group fed with diets containing 2 % or 4 % M. oleifera leaf extract, the histological alterations were reduced, level of liver enzymes, cortisol, upregulation of anti-oxidant enzyme, relative expression of cytochrome P450 gene and skin mucosal immune responses were normalized, with (4 %) M. oleifera leaf extract supplemented diet showing more prominent effects. These results suggest the protective and therapeutic roles of M. oleifera as a feed supplement in L. rohita against As induced toxicity.