Fish Diversity and Its Relation to Water Quality Parameters of Markonahalli Reservoir, Tumkur District, Karnataka, India
Chalapathi S. R.
Department of Studies and Research in Zoology, Tumkur University, Tumkur, Karnataka - 572103, India.
Lalitha H. M. *
Department of Zoology, University College of Science, Tumkur University, Tumkur, Karnataka - 572103, India.
*Author to whom correspondence should be addressed.
Abstract
Markonahalli Reservoir in Tumkur District, Karnataka, is used mainly for irrigation and fishing. This study assessed fish diversity and selected physicochemical water-quality parameters from February 2024 to January 2025 to examine reservoir conditions in relation to the recorded fish community. Fish were collected with the assistance of local fishermen using nets of different sizes and types, while water samples were collected monthly from four sampling sites. Water temperature, pH, turbidity, electrical conductivity, nitrate, sulphate, dissolved oxygen, and biological oxygen demand were analysed using standard methods. A total of 16 fish species representing 14 genera, seven families, and five orders were recorded, with Cypriniformes forming the dominant taxonomic group. The measured parameters showed spatial and seasonal variation across the sampling sites. Turbidity ranged from 2.75±0.418 to 6.25±0.7275 NTU, while electrical conductivity ranged from 403±11.358 to 856.33±14.263 µS/cm. Nitrate concentrations ranged from 2.425±0.025 to 4.825±0.307 mg/L, and sulphate ranged from 5±2.00 to 34±2.122 mg/L. Dissolved oxygen varied from 4.85±0.593 to 6.5333±0.177 mg/L, whereas biological oxygen demand ranged from 2.4667±0.134 to 4.4±0.548 mg/L. The findings provide baseline information on fish diversity and seasonal water-quality conditions in Markonahalli Reservoir and support continued monitoring for the sustainable management of its fishery and aquatic resources over time.
Keywords: Markonahalli reservoir, fish diversity, water quality parameters, DO