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Abstract

ABSTRACT The study provides information on the diversity, assemblage structure, distribution pattern, and composition of fish at several sampling locations along the river Diyung. In this study, fish fauna was collected from 8 selected stations of the river from January 2019 to December 2020. A total of 81 different fish species were identified, divided into 10 orders, 24 families, and 52 genera. The orders Cypriniformes, Siluriformes, Anabantiformes, and Synbranchiformes accounted for 88.88% of the total fish population and the remaining 12.12% is being contributed by other orders. The family Cyprinidae was found to be the most prevalent (40.74%). Minnows and barbs contributed the most (30.49%) among the 11 common groups of fishes identified. According to the IUCN status, 11.11% were near threatened (NT), 2.44% each of vulnerable and data deficient, 1.23% were endangered (EN), 6.17% were not evaluated (NE), and 76.54% were least concerned (LC). The Margalef species richness, Shannon-Weiner diversity indices showed higher diversity in the middle and lower stretches of the river. Subsequently, cluster analysis divided the samples into two different groups by sample sites. Group 1 comprised sites S6, S7, and S8 representing the lower stretches of the river and Group 2 comprised stations S1, S2, S3, S4 and S5, all of which were located in the middle and upper stream. The Canonical Corresponding Analysis revealed that environmental parameters have varied connotations with the fish occurrence, indicating species-specific adaptive potential. The parameters like temperature, turbidity, Dissolved Oxygen (DO) and velocity exhibited a positive correlation with fish abundance. Longest K-dominance curve formed at the station S-4 indicating the highest fish abundance. The findings will aid in the development of a reasonable exploitation and protection strategy for freshwater fish in the Diyung river.