PARAQUAT-INDUCED HISTOPATHOLOGICAL CHANGES ON THE GILLS, KIDNEY AND LIVER TISSUES OF ANABAS TESTUDINEUS (BLOCH 1792)

Abstract

Paraquat is the most widely used herbicide in agricultural activities for land preparation and weed control. Uncontrolled usage and poor waste management will introduce the chemical into the aquatic ecosystem due to agricultural runoff, causing harm to non-targeted aquatic species, especially fish. Therefore, this study was performed to evaluate the histological alterations of the gill, liver and kidney of the freshwater fish Anabas testudineus. Fish were exposed to four paraquat concentrations (2.0, 5.0, 12.0 and 15.0 mg/L) for 96 hours in controlled water parameters and without feeding. Following treatment, all fish were pithed and their gills, livers and kidneys were collected. Histopathological analysis with semi-quantitative scoring lesions were performed to determine the severity of the tissue changes in each fish organ. Histopathological changes in the gills after 96 hours of paraquat exposure showed lamella curvature, hyperplasia, edema, blood vessel congestion and necrosis compared with the control group. Histological changes, like degeneration in hepatocytes and necrosis were observed in the livers and kidneys exposed to 2.0-12.0 mg/L of paraquat. Prominent histopathological changes were observed in 15.0 mg/L of paraquat exposure, including nuclear pyknosis and necrosis. Overall, this study demonstrated deleterious effects of paraquat on the tissues of A. testudineus. The histopathological changes were proportional to the paraquat concentration and may impair organs’ vital functions which in turn affects the fish’s health.