This book is appropriate for the researchers of Fishery Science and aquaculture. It discusses comprehensive data about freshwater icthyodiversity and hydro-biological characteristics of downstream of Subansiri river. Upto dated status of IUCN for the fish species have been given here. Another aspects of this book are hazards of the river and socio-economic status of the fishers. Coloured picture of the fishes will help the researchers as well as the students to identify the freshwater fishes.