Benthos of freshwaters represents a highly discriminatory variable as these animals are confined to micro-habitats, constantly receiving natural matter produced in or blushing into an ecosystem. The Benthos can survive in polluted situation and a wide crowd of organisms belonging to different classes and orders. These include nematodes, annelids, arthropods and molluscs in a fresh water ecosystem. The Benthos are usually conquered by two main groups of organisms, oligochaete worms and chironomid larvae in addition to the third common group of mollusca. The crustaceans and various minor insect larvae are usually occurring in partial numbers. The quality of water affects species composition, abundance, productivity of freshwater benthic organism. The structure and composition of these organisms is a apparent indicator of water superiority.