Joydeep Chandra Das

Purpose: North-East India is recognized as one of the most species-rich freshwater fish regions in South Asia, characterized by complex topography, a dynamic geological history, and extensive river networks. Positioned at the intersection of the Eastern Himalayan and Indo-Burma biodiversity hotspots, the region harbors high taxonomic diversity and endemism. This review aims to synthesize current knowledge on freshwater fish diversity, spatial patterns of endemicity, evolutionary processes, and biogeographic affinities across major river basins, including the Brahmaputra, Barak, Chindwin–Irrawaddy, and Kaladan systems.

Results: Analysis of published literature indicates that tectonic uplift, river capture events, hydrological isolation, and paleoclimatic fluctuations have collectively driven lineage diversification and adaptive radiation, particularly in hill-stream and basin-restricted taxa. The ichthyofauna exhibits strong biogeographic affinities with both the Indian subcontinent and Southeast Asia, highlighting North-East India as a transitional zone for freshwater biodiversity. Despite its ecological and evolutionary significance, the region’s freshwater fishes face mounting threats from habitat degradation, hydropower development, overexploitation, and insufficient taxonomic resolution.

Conclusion: The review identifies critical knowledge gaps and emphasizes the need for integrative taxonomic approaches, basin-scale phylogeographic studies, and habitat-focused management strategies. Implementing these measures is essential for conserving the unique ichthyofaunal assemblages of North-East India and ensuring the long-term preservation of this globally significant freshwater biodiversity hotspot.

DOI: 10.22271/23940522.2026.v13.i1a.1161

Pages: 01-06  |  121 Views  73 Downloads