This book helps to study basic concepts of biosystematics and importance of classification; variation in structure-form-skin-colouration-scales-mouth-jaws-teeth-fins-spines and other structures used in taxonomic studies; induced breeding techniques; seed and brood transportation; external morphology and internal organization of elasmobranchs and teleost fishes; feeding habits in various group of fresh water and marine fishes, prawns, crabs, lobsters and cephalopods; qualitative and quantitative estimation of food consumption based on experimental studies and stomach content analysis; seasonal...