Fish Diversity of Tamakoshi River and its Major Tributary Singati River, Dolakha, Nepal

Abstract

The current study examines fish diversity, abundance and its relation with water quality in the Tamakoshi and Singati Rivers over three seasons: Post-Monsoon, winter, and PreMonsoon from 2023 to 2024. This study also focuses the identification of spawning grounds, and the social status of local fishermen. Nine sampling stations were selected along in two river system and fish samples were collected using cast net (5mm mesh size) with the help of local fishermen. A total of 7 species belonging to 2 Orders, 3 Families, and 6 Genera were recorded with 536 individuals catch. The Order Cyprinidae was recorded to be the most dominant family followed by the Sisoridae and Psilorhynchidae. Psilorhynchus pseudecheneis was the most dominant (31.16%) species, followed by Schizothorax progastus (21.26%), and Schizothorax richardsonii (15.29%). Station TR5 had the highest Shannon Weiner’s diversity index (H'= 1.881), while Station TR1 had the lowest (H'= 1.36). The maximum Margalef's richness (d= 1.731) was observed at station SR4, whereas the minimum (d= 0.8867) was at station TR1. Similarly, the highest Pielou’s evenness Index (J= 0.9906) was recorded at station TR3 and the lowest (J= 0.7733) at station SR4. The fish assemblage structure was positively correlated with environmental factors like water temperature, pH, dissolved oxygen, velocity, total dissolved solids, and hardness. Additionally, the identification of spawning grounds also reflects the conservation initiatives for fish diversity and habitats.