Abstract
Ivermectin is broad spectrum antiparasitic drug. Fish acute toxicity tests were carried out in zebra fish (Danio rerio) and catla fish (Catla catla) to assess the comparative tolerance to ivermectin induced toxicity and pathological alterations. The fishes were exposed to various concentrations of ivermectin (1, 3, 5, 7 and 9µg/l) and observed for behavioral changes in swimming pattern, maintaining equilibrium, pigmentation and mortality at various time intervals (24, 48, 72 and 96h). The brain and the liver samples were collected from the experimental fishes every 24h for histopathalogical analysis. The behavioural changes and mortality in fishes increased with the increase in ivermectin concentration and exposure time. Neurotoxic (gliosis and neuron degeneration) and hepatotoxic changes (necrosis and acute hepatitis) were observed in the brain and liver of zebrafish respectively when exposed to 7µg/l of ivermectin for 96h. In catlafish, the same concentration (7µg/l) of ivermectin induced neuronal degeneration and necrosis in brain and hepatotoxic signs (hepatic cell degradation, vacuolations) in liver at 24 h exposure. The results of this study conclude that zebrafish is more tolerant to higher concentrations and prolonged exposure to ivermectin compared to catla fish
