Toxicity of Organophosphorus Insecticide – Methyl Parathion on Rohu (Labeo rohita)

Fresh water fish, Labeo rohita was exposed to sub- lethal concentrations (0.25, 0.5 and 1.0 mg l -1) of the organophosphorus insecticide, methyl parathion (MP) for 15, 30 and 45 days. Aspartate and alanine amino transferase activity increased with increasing pesticide concentration, suggesting tissue damage and muscular harm due to exposure to methyl parathion. The increase in the activity of alkaline phosphatase suggests an increase in lysosomal mobilization and cell necrosis due to methyl parathion toxicity. The results clearly indicate that the organophosphorus insecticide methyl parathion is toxic at sublethal level and it affects intermediary metabolism of Labeo rohita.