Vol. 9, Issue 10, Part A (2025)

Acephate (O,S-dimethyl acetyl phosphoramidothioate), a widely used organophosphorus insecticide, poses significant risks to both human health and the environment. Its metabolite, methamidophos, is highly toxic to aquatic organisms, birds and mammals. This study investigates the acute and sublethal toxicity of acephate in fingerlings of Cyprinus carpio through histological evaluation and depuration analysis. Acute toxicity was assessed via 96-hour LC₅₀ tests, revealing a lethal concentration of 850.41 ppm. Sublethal toxicity trials were conducted over 28 days using two concentrations: 1/5^th LC₅₀ (170.082 ppm) and 1/10^th LC₅₀ (85.041 ppm). Histological analysis of liver tissues exposed to acephate revealed significant alterations, including hepatocellular degeneration, cytoplasmic vacuolation, necrosis, and pyknotic nuclei. Following 28 days of exposure, the fish were transferred to pesticide-free water to observe depuration and tissue recovery. Gradual histological improvement indicated the potential for tissue regeneration post-exposure. These results highlight acephate’s harmful effects on fish health and emphasize the importance of histopathological biomarkers in ecotoxicological assessments. The findings call for stringent regulations and continued research to establish safe pesticide residue limits in aquatic environments.