Lethal toxicity of deltamethrin and histological changes in the vital organs of fingerlings of Labeo rohita

Abstract

The investigation was carried out to find out the lethal concentration (LC50) and safe concentration for deltamethrin on fingerlings of Labeo rohita by acute toxicity test along with the observations on associated histological alterations in the vital organs upon sub lethal exposure. The static bioassay methodology was followed to find out the 24h, 48h, 72h and 96 h LC50 values for deltamethrin. 3 replications were taken for each treatment. The safe application factors for deltamethrin were 1.00µg/l and presumable harmless concentration were 0.117 µg/l. Sub lethal studies were conducted by exposing the fishes to the 1/10th of the LC50 values for deltamethrin separately for a period of 30 days with provision of food, aeration and water replenishment. The histopathological alterations observed includes degenerated hepoto-pancreatic tissue, appearance of blood streak among hepatocytes, formation of blood cells among hepatocytes, swelling of the hepatocytes, diffused necrosis in liver. Histopathological changes observed in gill includes swollen branchial arch with accumulation of infiltrating cells, etc.