Histological and Behavioral Alterations of the Striped Catfish P. Hypophthalmus Exposed to Chlorpyrifos

The striped catfish, P. hypophthalmus, was subjected to a bioassay to evaluate the lethal toxicity (LC₅₀) of the commercial-grade organophosphate pesticide, chlorpyrifos (20% EC). The LC₅₀ of chlorpyrifos to P. hypophthalmus was found to be 0.106 mg L^-1. For the sub-lethal toxicity study, the fishes were exposed to two sublethal concentrations 0.0106 mg L^-1 and 0.0212 mg L^-1 (1/10^thand 1/5^th of LC₅₀) for 30 days. At different concentrations of chlorpyrifos exposed fish showed behavioral alterations such as rapid swimming, loss of equilibrium, severe slime production, swimming at the sides, signs of stress, etc. Histological alterations observed in the gill include curling of secondary lamellae (SL), lifting epithelial lamellae, swollen of SL tips, fusion of SL, hyperplasia, disorganization of lamellar, degeneration of secondary lamellae and severe narcosis in fish gills. Liver alterations include dilation of sinusoids, hyperplasia, cytoplasmic vaculation, hemorrhage, malanomacrophages aggregation, necrotic hepatocytes and pyknotic nucleus. Kidney alterations include reduce lumen of renal tubule, increase bowman space or tubular lumen, glomerulus shrinkage, congestion of haematopoietic tissue, hyperplasia and degeneration glomerulus. The finding of this study indicates that chlorpyrifos is toxic and have adverse effects on fish.