Even though literature is available on the nutritional value of many estuarine and marine fishes, studies relating to the biochemical composition of Platycephalus indicus, Sorsogona tuberculate, Thysanophrys carbunculus, Grammoplites scaber, Suggrundus rodericensis and Scomberomorus commerson have not been carried out so far. The present investigations are therefore undertaken  to study the biochemical constituents like protein, carbohydrates, lipids and calorific value in various body tissues like muscle, liver and gonad of the above mentioned commercial fishes of Parangipettai (Porto Novo) waters.