Biochemical Biomarkers and Organ-Level Histopathology in African Catfish (Clarias gariepinus) Exposed to Sublethal 2,2-Dichlorovinyl Dimethyl Phosphate (Dichlorvos) Concentrations

Aquatic ecosystems are becoming increasingly affected by chemical pollution, especially pesticide contamination from agriculture and domestic pest control. Dichlorvos (2,2-dichlorovinyl dimethyl phosphate) is widely used in developing countries due to its high solubility, rapid action, and broad effectiveness. It is increasingly introduced into surface waters through runoff, leaching, and improper disposal. This study assessed the biochemical and histopathological effects of sublethal concentrations (0.0 ml/L, 0.9 ml/L, 1.8 ml/L, 2.7 ml/L, 3.6 ml/L, 4.5 ml/L) of dichlorvos in water on Clarias gariepinus (African catfish) over a 28-day exposure period. Aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatinine, alanine aminotransferase (ALT), total protein, albumin, and globulin, as well as physicochemical properties (temperature, pH, dissolved oxygen, total dissolved solids, and electrical conductivity) of the water, were measured. Physicochemical properties of the water remained largely stable across treatments, except for significant reductions in total dissolved solids and electrical conductivity, suggesting interactions between dichlorvos and the aquatic medium. The study revealed a significant increase (p<0.05) in AST, ALP, and creatinine in exposed fish, while ALT showed a non-significant increase, indicating hepatic and renal impairment. Total protein, albumin, and globulin showed dose-dependent decreases, suggestive of disrupted protein synthesis. Histopathological examination revealed diffuse hepatocellular vacuolar degeneration in the liver and hyperplasia and fusion of secondary lamellae in the gills of exposed fish. The kidneys exhibited no visible structural lesions. The findings highlight the vulnerability of non-target aquatic organisms to dichlorvos contamination from agricultural and domestic sources.