Evaluation of Acute Toxicity Levels and Ethological Responses Under Tetrachlorocatechol Exposure in Common Carp,Cyprinus carpio (Linnaeus)

Tetrachlorocatechol (TCC) is one of the most toxic chlorinated catechol produced by the chlorobleaching of pulp and frequently found in the kraft pulp mill effluents. Toxicity of TCC to common carp, Cyprinus carpio and their ethological changes were evaluated in the present study. The 24, 48, 72 and 96 h LC₅₀ values of TCC to C. carpio were 4.73, 3.95, 3.20 and 2.43 mg/l respectively. The mortality rate of C. carpio showed significant relationship (p < 0.05) at different exposure times (24, 48, 72 and 96 h) in different treatments of TCC (2, 3, 4, 5 and 7 mg/l). On the other hand, a significant correlation (p < 0.01) was observed between the mortality rate of fish with all the concentrations of TCC. Mean opercular movement in the fish increased significantly with the increasing dose and time of exposure to TCC indicating acute respiratory distress. The jerky movement, somersaulting, circular movement and mucus secretion of fish increased gradually with the increasing concentrations and exposure times of TCC for adapting a compensatory mechanism to derive energy in order to avoid stress due to toxicity.