TOXIC EFFECT OF ORGANOPHOSPHORUS INSECTICIDE – METHYL PARATHION ON ALT, AST& LDH ACTIVITY IN FRESH WATER FISH HETEROPNEUSTES FOSSILIS

The freshwater fish Heteropneustes fossilis was exposed to sublethal concentrations (0.25, 0.5, and 1.0 mg L⁻¹) of the organophosphorus insecticide methyl parathion (MP) for exposure periods of 15, 30, and 45 days. The activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) showed a concentration-dependent increase, indicating tissue damage and muscular impairment resulting from MP exposure. Similarly, elevated LDH activity suggests enhanced lysosomal mobilization and cellular necrosis. These biochemical alterations clearly demonstrate that methyl parathion exerts toxic effects even at sublethal concentrations, disrupting intermediary metabolism and indicating significant physiological stress in Hteropneustes fossilis.