The publication “Inland Fish Diversity” reflects restructured information on freshwater fish diversity of Karnataka, Kerala, Tamil Nadu and United Andhra Pradesh along with estuarine fish diversity of Tamil Nadu and Vembanad Lake of Kerala with a note on systematic placement as per the latest taxonomic revisions of fish species, together with their environment, endemic or exotic status, maximum size, human use (existence or nonexistence of fishery, aquaculture, ornamental or game fish) and conservation status as per IUCN criteria. It is anticipated that this publication will deliver basic information on the inland fish diversity of south India and offer better inputs for scientific management and utilization of the resources on sustainable manner.