Effect of nanoformulated cypermethrin, a parasiticide in Labeo rohita fingerlings: impact on biochemical, haematological, and stress response.

Cypermethrin is a pyrethroid insecticide used in aquaculture farms against ectoparasites. The conventional pesticide formulations are now being found to be greatly ineffective at low dosages, and their indiscriminate usage may cause undesired effects in ecosystems. So, the current study was designed to develop a nanoformulation of cypermethrin that would have many advantages over conventional pesticide formulations, and the toxic effects of this formulation were then tested on the carp Labeo rohita fingerlings. The 96-h LC₅₀ was estimated at 0.018 mg L^-1 after the acute toxicity study. Chronic toxicity studies were carried out, exposing the fish to two sublethal doses via 1/10th (C1) and 1/50th (C2) of 96-h LC₅₀ for a period of 45 days. The nanoformulation exposure caused a significant reduction in the brain AChE enzyme activity. Catalase and glutathione-s-transferase enzyme activity in the gills and liver increased significantly, as did superoxide dismutase enzyme activity in the kidney. Serum total protein, triglycerides, cholesterol, and some serum enzyme activities decreased. In contrast, white blood cells, red blood cells, haemoglobin, and hematocrit levels decreased only in fish exposed to a higher dose. As baseline information, these findings may aid in understanding the toxic effect of nanoformulated cypermethrin on finfish.