Optimum feed requirement and ingestion rate of pearl oyster Pinctada fucata spat of three different size groups were studied. The spat were fed Chaetoceros sp. at different concentrations to study the feeding rate. Spat in the size group 5-9 mm had the maximum growth when fed at a concentration of 3 lakh cells ml-' spat-' day-'. Spat in the size range 10-14 mm and 15-19mm showed the maximum growth at a feed concentration of 6 lakh cells and 9 lakh cells respectively. The growth rate was found to be higher in smaller group with lower concentration of feed whereas growth increment was higher in larger group at a higher concentration. The ingestion rates were found to be directly related to the size of the spat. Larger the spat, more is the rate of ingestion hr'. The results of this study could be taken advantage of in the hatchery and onshore culture systems for maintaining optimum algal densities for raising oyster spat.

Feeding and ingestion rates in pearl oyster