Indian Ocean harbour about 4000 fish species. Except identifying characters and taxonomic status of the species, it is practically impossible to describe the bionomics of each of the four thousand species, since studies have not been made for all and reliable informations are not available in respect of many uneconomical species. Thus in a dynamic ocean, with so many regional micro-climatic and hydrological changes, many of the commercially important fish species fluctuate in their seasonal inshore migration resulting appearance of huge fish shoals forming a good fishery in some years, while there is a failure of the fishery in other years due to the disappearance of the shoals. Considering this dynamic condition of the sea and the dynamic nature of fish species, regional, area wise, depth wise movement and their assemblage have been described in the book. In the book, besides, describing identifying characters of major groups of fish, details of pelagic commercially important oceanic tuna, biological characteristics of some economically significant species of each of major fish groups have been mentioned with special reference to the seas around Indian Sub-Continent. Occurrence and capture of species forming commercial fishery from seventeen fishing grounds along the Indian coasts have been outlined in the book. Significant details in respect of more than four hundred fish species of economic importance is an additional attraction of the book.The book contain numerous diagrams sketches and photographs.