Document Type: Primary Research paper
The present study was undertaken to investigate the acute toxicity of cadmium, a heavy metal widely detected in the aquatic environment due to natural effects and anthropogenic activities, in freshwater teleost, Channa punctata (Bloch). The experiments for the bioassay were performed in semi-static test condition according to the standard guidelines. The behavioural changes in the fish were observed for all tested concentrations of the metal. The data obtained for bioassay were analyzed for median lethal concentrations (LC50) of the metal by SPSS computer software, Finney’s Probit analysis and Trimmed Spearman-Karber’s method. The LC50 values, estimated by SPSS, with 95% confidence level were found to be: 26.88 (21.69-71.68), 18.76 (17.13-20.81), 16.70 (14.77-17.96) and 14.95 (13.13-15.88) mg l-1 for dissolved metal concentrations, at 24, 48, 72 and 96 h exposure durations respectively. All three methods showed good agreement among the estimates. Furthermore, the exposed specimens showed dose and duration dependent abnormal behaviour and hyperactivity.