Limnological Assessment of Benisagar Reservoir (Madhya Pradesh, India) with Special Reference to Ichthyofaunal Diversity and Water Quality Dynamics

Abstract

The present study assessed the limnological characteristics and ichthyofaunal diversity of Benisagar Reservoir, Madhya Pradesh, India, with emphasis on seasonal changes in water quality and fish-community structure. Sampling was conducted from January 2024 to December 2025 at four stations representing the inlet, pelagic, littoral, and outlet zones. Fish were sampled monthly using conventional fishing gear with the assistance of local fishers, and specimens were identified using standard taxonomic keys. Water-quality parameters were measured according to standard procedures and included temperature, pH, electrical conductivity, dissolved oxygen, turbidity, total were identified using standard taxonomic keys. Water-quality parameters were measured according to standard procedures and included temperature, pH, electrical conductivity, dissolved oxygen, turbidity, total dissolved solids, nitrate, and phosphate. A total of 22 fish species, representing 5 orders, 8 families, and 15 genera, were recorded during the study period. Cyprinids were the dominant group, and economically important species such as Catla catla, Labeo rohita, and Cirrhinus mrigala were frequently recorded. Seasonal variation was evident in both fish diversity and water quality across the reservoir. Post-monsoon conditions supported greater fish diversity, whereas pre-monsoon conditions were associated with higher temperatures, lower dissolved oxygen concentrations, and reduced diversity. Nutrient concentrations increased during the monsoon, suggesting runoff-driven enrichment. The findings indicate that Benisagar Reservoir supports a moderately diverse fish assemblage and requires regular monitoring to conserve aquatic biodiversity and sustain fisheries productivity.