Sensitivity of Common Carp, Cyprinus carpio (Linnaeus, 1758) to the Grey List Metal, Zinc under Laboratory Condition

In the present investigation, acute toxicity of the grey list metal, Zinc was carried out under laboratory condition to Cyprinus carpio (Linnaeus, 1758). The 96 h LC₅₀ value of zinc with 95% confidence limits to C. carpio was recorded as 15.804 (15.083-16.721)mg/l. None of the unexposed fish died during the bioassay. Mortality rate of the exposed fish to the toxicant significantly (p<0.05) varied over the control at all concentrations during every 24h time interval. Significant relationship (p<0.05) was also observed between mortality rate and exposure times (24, 48, 72 and 96 h) at all concentrations of the toxicant except 13.5, 14.5 and 15.0 mg/l. Toxicity factor for the toxicant to the organism increased with the time of exposure. The behavioral responses in respect of activeness, body balance, swimming and mucous secretion were also changed in the exposed fish. The intensity of behavior altered with the increasing doses and progress of time of exposure. The opercular movement of the fish increased significantly (p<0.05) over the control with increasing concentration but decreased significantly (p<0.05) with the progress of time of exposure at all concentrations.