Fish, Channa punctatus were exposed to sublethal concentrations of 10, 15 & 25 mg/ 1 zinc for 8, 10 and 15 days. Behavioural changes, body weight, liver weight and hepatosomatic index were noted at each interval. Exposed fish showed reduced swimming activity and fin movements along with increased surfacing frequency, mucus secretion and opercular movements. A non-significant decline was noted in body weight which was accompanied by a significant decline in liver weight and hepato-somatic index. These changes were reversible and dose and time dependent. For post exposure recovery these fish were transferred back to normal tap water for fifteen days. Behavioural changes return towards normal though body weight continues to decline. Liver weight and hepatosomatic index show A marginal increase. Since behaviour of fish is immediately influenced by exposure to zinc, it can act as a good indicator of pollution. Liver weight and HSI are also sensitive indices.
