ABSTRACT The present study investigates the assemblage and distribution patterns of ichthyofauna in the lowland streams of the Shivalik Himalayan region, Himachal Pradesh, within the Beas River basin. Four streams were surveyed to examine fish diversity in relation to environmental variables. Water quality parameters were assessed to analyze the water quality and its impact on fish species assemblage, using Pearson correlation coefficient and Weighted Arithmetic Water Quality Index (WAWQI) method for correlation and quality measurement. Results indicated that these streams provide diverse habitats for numerous fish species. A total of 24 fish species belonging to seven orders and 10 families were recorded. Order Cypriniformes is the dominant order, comprising 14 species. With an increase in habitat heterogeneity, the number of fish species increases downstream. Cluster analysis revealed distinct habitat preferences among fish species, with assemblage varying across pools, riffles, and runs. Canonical Correspondence Analysis (CCA) highlighted the association between certain fish families and environmental variables. Fish species showed differential correlation with varied physicochemical parameters, with species such as Tor putitora and Tariqilabeo diplochilus preferring water with low temperature and high dissolved oxygen (DO), whereas Channa sp. and Pethia sp. were found in habitats with low DO. These findings underscore the ecological heterogeneity of the streams and the importance of microhabitat diversity in supporting fish assemblage.
Sharma et al. (Sat,) studied this question.