Freshwater fish diversity and habitat assessment with a focus on Pethia reval in Pusweli Oya, Kelani River Basin, Sri Lanka

Abstract

Abstract. Priyadarshana PHMGC, Vijethilaka ULNL, Fernando MT, Paranagama SD. 2024. Freshwater fish diversity and habitat assessment with a focus on Pethia reval in Pusweli Oya, Kelani River Basin, Sri Lanka. Intl J Bonorowo Wetlands 14: 105-111. The Pusweli Oya, a tributary in the Kelani River Basin was investigated preliminary to assess the freshwater fish diversity with a particular focus on the endangered endemic species Pethia reval. This study highlights the urgent need for conservation actions to protect these unique ecosystems. Five distinct sites were selected for the study, and sampling was conducted from August to October 2024 using snorkeling, hand nets, and trawl nets complemented by measurements of physio-chemical parameters, including temperature, pH, and flow rate with anthropogenic activities. A total of 29 freshwater fish species were recorded, representing eight orders and 12 families, with Cyprinidae being the most dominant family. Among these, 10 species were endemic, highlighting the area's ecological importance. Pethia reval was recorded at most of the selected sampling sites but was absent in one sampling site, which displayed a lower pH and increased anthropogenic activities than other sites. These conditions and the presence of aquatic plants likely impacted the species' distribution, emphasizing its sensitivity to habitat disturbances. Findings reveal that sites with stable water quality and minimal anthropogenic influence are essential for sustaining diverse fish populations and conserving P. reval and other endemics. This research underscores the need for immediate area-based conservation actions to mitigate human impacts and maintain ecological balance within the Kelani River basin. Those area-based conservation activities will contribute to broader conservation throughout the country with a special focus on range-restricted and nationally important freshwater fish fauna on the island. Future studies should focus on longitudinal assessments to strengthen conservation strategies for Sri Lanka's endemic and native freshwater fish.