Behavioural responses and acute toxicity of Clarias batrachus to synthetic pyrethroid insecticide, λ- cyhalothrin
G. Indira Rani and A. K. Kumaraguru
Toxicity tests are an important component for assessing the impact of chemicals on aquatic ecosystems because they indicate toxic effects of chemicals. In aquatic toxicity tests, groups of selected organisms are exposed to test materials under defined conditions to determine potential adverse effects. Bioassay tests were conducted on fresh water air breathing fish Clarias batrachus to evaluate the acute toxicity of synthetic pyrethroid λ- cyhalothrin insecticide by determining their LC50 after 24, 48, 72 and 96 h exposure. The safe concentration of this biocide was calculated on the basis of LC50 for 96h. From the results obtained it was observed that the LC50 values of 96 h were found lowest among all the exposure periods. The 96 h LC50 values provide a useful means of comparing the relative acute lethal toxicity of specific toxicants to organisms under specific conditions. Susceptibility of catfish, Clarias batrachus to lethal effect of synthetic pyrethroid was found to be duration and concentration dependent as mortality was increased with an increase in its concentration in the present study. Behavioural characteristics are obviously sensitive indicators of toxicant effect. Many chemical contaminants target specific physiological systems and exert their effects on behavior. Fish in toxic media exhibited irregular, erratic swimming movements, hyper excitability, loss of equilibrium spiraling, loss of balance, rapid respiration, light discoloration, surfacing, and gulping air. The present investigation was designed to elucidate the acute toxic effect of λ- cyhalothrin insecticide on the toxicity and behavior of air breathing fish Clarias batrachus.