Survey of the fish genetic resources conducted, for the first time, since 2000,, in the river Barak in Assam and its tributaries, viz., Jatinga, Sonai and Dhaleswari; and, in rivers Tuirial and Gomati in Mizoram and Tripura respectively, revealed the occurrence of 103 speices of fishes belonging to 60 genera, 24 families and 10 Orders. Highest species richness was observed in Barak (52) followed by Jatinga (51), Sonai (47), Dhaleswari (33), Tuirial (30) and Gomati (47) with concomitant highest species diversity (Shannon-Wiener) being reflected in Jatinga (H=2.18) followed by Barak (H=1.45), Sonai (H=1.40), Dhaleswari (H= 1.12), Tuirial (H= 1.27) and Gomati (H=1.36). Zoogeographically, these fishes could broadly belong to two broad groups, viz., the primary freshwater group and the peripheral class; while , ecomorphologically, they could be included under four distinct groups. Among the fish assemblage, cyprinids depicted the highest contribution in river Tuirial and lowest in river Barak with their occurrence revealed in pools, pool edges, backwater pools, riffles and riffle edges. Habitat diversity revealed differences in valley segment among the different rivers, some portraying alluvial while others colluvial, the latter being found to portray a diversity of microhabitats to make it colonisable by the rheophilic fishes. Fish cover have been found to be mostly turbulence and depth types, the former the ranging from 2-25 %, while the total cover among all the studied rivers ranged from trace (< 5%) to moderate (5-20 %). Substrate types in the hilly portions of the surveyed rivers were found to be dominated by gravels, cobbles, boulders and bedrocks while in the plain portion of the rivers, the substrate type mostly consists of fines. It is mesoriparian in all the studied rivers but the riparian but the riparian vegetation varies from shrubs to trees in different rivers. Signs of erosion have been observed in all the rivers. Inspite of all our efforts, much of our bewildering diversity of fish resources have come under severe threat, which suggests immediate conservation measures along with concomitant development of fisheries through community participation and involvement of womenfolk. Extent of success in this direction could be revealed through feedbacks from the usergroups regarding their options for management of resources, their developmental aspirations, their modus operandi for resource conservation and so on. Our study revealed a general eagerness among the people for fish conservation. Attempts are being made to declare certain sites in rivers Dhaleswari and Jatinga as `aquatic sanctuaries' in order to protect critically endangered fishes like Tor progenies .

 The Northeast India, comprising of seven provinces, viz., Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram and Tripura, is one of the global Hotspots for faunal biodiversity. These provinces with their unique topography, diverse physiographic features and varied watershed patterns are a lucrative field for ichthyological studies with innumerable hill streams, rivers and wetlands. Nevertheless, the region is fed by two major drainage systems. The northern region is drained by the Brahmaputra and its tributaries and the southern region by the Barak and its tributaries. The eastern part, consisting of portions of Manipur, Nagaland and Mizoram, is partly drained by the Chindwin basin.

Department of Life Science, Assam (Central) University,
Silchar-11, India and
Conservation Forum, Silchar-5, Assam, India