Healthy C. punctatus (18−20 g in weight; 9−11
cm in length) were collected from local freshwater
bodies in and around Annamalai University,
Annamalainagar. Fish were separately maintained at 27±1°C in 1,000 L tank with continuously aerated anddechlorinated tapwater (pH 7.2−7.4; hardness 185-200 mg L-1 as CaCO3; alkalinity 170−175 mg L-1 as CaCO3) at least one month prior to the experiments.
The laboratory photoperiod was 12 h D: 12 h L. Fishwere fed with boiled chicken eggs and small pieces of earthworm on alternate days and then 60% water wasrenewed everyday