The effect of waterborne zinc on survival, growth, and feed intake of Indian major carp, Cirrhinus mrigala (Hamilton), advanced fry was studied under laboratory condition. Survival rates of C. mrigala advanced fry (2.71±0.49 g) after 30 days exposure to control (0.01), 0.03, 0.06, 0.10, and 0.15 mg/L zinc using the static renewal method in freshwater at pH 7.3±0.2, temperature 26±2°C, and total hardness 114±16 mg/L as CaCO 3 were 100%. Growth of the fish exposed to 0.10 and 0.15 mg/L of zinc was significantly lower (P<0.05) than in control (0.01), 0.03, and 0.06 mg/L of zinc after 30 days of exposure. However, there were no significant differences (P>0.05) in fish growth between 0.03 and 0.06 mg/L zinc concentrations. Feed intake rates were significantly (P<0.05) reduced in the fish exposed to 0.10 mg/L and higher levels of zinc. The zinc accumulation in the whole body of the fish increased with increasing concentrations of the metal.

The effect of copper on survival, growth and feed intake of Indian major carp, Cirrhinus mrigala (Hamilton) fry (0.92 +/- 0.28 g) was studied for 60 days. Survival rates of the fish exposed to control (0.02), 0.10, 0.15 and 0.23 mg L(-1) copper were 100%, 83 +/- 3%, 58 +/- 6%, and 50 +/- 4%, respectively. Average daily growth was significantly (p < 0.05) lower at 0.15 and 0.23 mg L(-1) of copper. There was almost no growth at 0.23 mg L(-1) of copper. Feed intake rates reduced significantly (p < 0.05) at all the copper treatments. The copper accumulation in the fish increased with increasing concentrations of the metal.

A comparison between middle-aged and old lizards revealed no significant age change in glucose-6-phosphate dehydrogenase activity of liver and kidney. Thermal inactivation at 51 ± 1°C induced a significantly higher degree of decline in enzyme activity of tissues of old than that of middle-aged lizards. The increase in thermolability of enzyme in liver and kidney of ageing lizards suggests an accumulation of altered enzyme molecules.

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