Brahmaputra River is one of the longest rivers in the world. It flows through Tibet, India (Arunachal Pradesh and Assam) and Bangladesh before reaching its delta with the Bay of Bengal. In Assam, the River traverses a total length of about 900 km and receives 103 notable tributaries from both sides, 65 from the north bank and 38 from the south bank. In the present investigation, effort has been made to study the fish faunal diversity of the River along with its distributional pattern throughout the length in Assam. Certain habitat attributes such as Plankton populations, Water and Soil quality of the river, has also been estimated to throw some light on its habitat ecology.