Seasonal Variation in Water Quality and Reproductive Performance of Labeo rohita (Hamilton, 1822) in the Godavari River at Nanded, Maharashtra, India

Abstract

Seasonal variation in river-water quality may influence the physiological condition and reproductive biology of freshwater fishes. The present study examines seasonal variation in physicochemical water characteristics, selected potentially toxic elements, and reproductive parameters of Labeo rohita (Hamilton, 1822) in the Godavari River at Nanded, Maharashtra, India. Three sampling stations were considered, and observations were organised into summer (March–May), monsoon (June–September), and winter (October–February) periods. Water-quality parameters included temperature, pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), turbidity, and total hardness. Selected elements included lead, cadmium, chromium, copper, and zinc. Reproductive assessments included total length, body weight, ovary weight, gonadosomatic index (GSI), and absolute and relative fecundity. The results showed the highest water temperature during summer (33.8 ± 1.2 °C) and the highest turbidity during monsoon (65 ± 15 NTU). Dissolved oxygen was highest in winter (7.2 ± 0.4 mg/L), whereas BOD₅ was highest in summer (4.2 ± 0.7 mg/L). Among the reported metal concentrations, zinc had the highest numerical concentration in each season. The reproductive summaries indicated a higher GSI during monsoon (10.1 ± 2.0%) than during summer (5.2 ± 1.4%), while the winter value was lower (1.7 ± 0.6%). Absolute and relative fecundity were reported for summer and monsoon, but not winter. These patterns provide a framework for examining seasonal associations between water quality and fish reproductive condition. Conclusions regarding pollution-related reproductive impairment cannot be established without validated observations and appropriate statistical analysis.