The Biobrio 12(3&4), 2025

Ichthyofaunal Diversity and Seasonal Dynamics of the Kosi River near Supaul, Bihar, India: Implications for Conservation

Neha Shikha & B. P. Singh

ABSTRACT:

The present investigation provides a detailed assessment of ichthyofaunal diversity and seasonal dynamics of the Kosi River near Supaul, Bihar, India. The study was conducted from January to December 2024 across three representative sampling stations, namely Bhimnagar, Nirmali, and Triveniganj, covering upper, middle, and Lower River stretches. Fish samples were collected fortnightly using a combination of traditional and standard fishing gears. Specimens were preserved in 8% formalin and identified using standard taxonomic keys. A total of 24-32 species were recorded across the study sites, with maximum species richness observed at Nirmali (32 species), followed by Bhimnagar (28 species) and Triveniganj (24 species). Diversity analysis using Shannon-Wiener and Simpson's indices revealed peak diversity during the monsoon season (H’ = 3.21; D = 0.91), indicating favorable ecological conditions. Seasonal fluctuations in diversity were strongly linked with hydrological changes, including increased discharge, habitat connectivity, and nutrient influx during monsoon. The study highlights the ecological significance of the Kosi River as a productive yet vulnerable freshwater system. Increasing anthropogenic pressures, including habitat alteration and overfishing, may threaten its biodiversity. The findings provide a baseline for future monitoring and emphasize the need for sustainable conservation strategies.

Keywords:    

Ichthyofauna, Kosi River, biodiversity indices, seasonal variation, freshwater ecology

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