Results and Discussion
Food composition: The food mainly consisted of plants namely the seaweeds (green and brown algae) and to some extent the seagrass. There was not much variation in the food composition during 2005-06 and 2006-07 (Fig. 2) except the presence of zoobenthos like polychaete worms, small crustaceans (shrimps, crabs) and bivalves (about 4.7%) during 2005-06. The contribution of semidigested matter was high (49.7%) during 200506 than during 2006-07 (26.7%). The presence of considerable quantites of semidigested matter might be due to the rapid digestion that takes place in the tropical waters as the metabolic rate is high (Kalita and Jayabalan, 2000).