Ichthyofaunal Diversity and Abundance in the Longnit River, Karbi Anglong, Assam, India: A Preliminary Assessment

The present study aims to provide a comprehensive assessment of the ichthyofaunal diversity, abundance, and conservation status of fish species in the Longnit River, Karbi Anglong, a relatively less documented region with limited studies on its biodiversity. An extensive survey was conducted from November 2020 to June 2021, in two distinct catchment areas of the river using standard methodologies. A total of 23 species belonging to 14 families and 6 orders were identified, with Cyprinidae being the most dominant family. Notable genera, such as Botia, Crossocheilus, Garra, Glyptothorax, Labeo, and Psilorhynchus, were recorded, which are characteristic of such fast-flowing hillstream ecosystems. Although continuous monitoring is essential to assess potential threats, the IUCN conservation status assessment revealed that the majority of species fall under the Least Concern category. Diversity indices reveal a high level of species richness and evenness with the Shannon Diversity Index (H') = 3.0, The Simpson's Index of Dominance (D) = 0.05, and Simpson's Index of Diversity (1-D) = 0.95 indicating a rich diversity and low dominance by any one species. As a preliminary study, these results on the fish diversity and abundance of Longnit River provide fundamental data for the development of targeted conservation strategies to preserve the aquatic hill stream fish fauna of this underexplored ecological zone.