Fish diversity assessment of Pakke river: A preliminary study from the Eastern Himalayas.

This study presents comprehensive assessment of fish diversity in the Pakke River system, located within the Pakke Tiger Reserve of Arunachal Pradesh, Eastern Himalayas. Systematic fish sampling was conducted in 2023 and documented 13 species across three orders and seven families, with Cypriniformes dominating the assemblage. Diversity indices, including Shannon-Wiener (H’=2.09), Simpson (D=0.84), Margalef (2.71), and Pielou’s evenness (0.81), indicate moderate to high species diversity and a balanced community structure. Notably, threatened species such as Cyprinion semiplotum (Vulnerable), Aborichthys kempi and Ompak pabda (both Near Threatened) were recorded, underscoring the conservation significance of this relatively pristine river system. The integration of traditional ecological knowledge with scientific sampling enhanced species detection, particularly of cryptic taxa. This baseline biodiversity data provides critical insight for future conservation planning and highlights the river’s role in maintaining freshwater biodiversity within the Eastern Himalayan biodiversity hotspot.