Seasonal And Spatial Patterns Of Nematode Infection In Commercial Fish Species Of The River Ganga At Kanpur And Environmental Correlates

Abstract

This study examines how nematode infections vary seasonally and geographically among economically important freshwater fish species that live in the Kanpur area of Uttar Pradesh, India, along the Ganga River. Due to human demands, industrial effluents, and home discharge, the Ganga River—a lifeline for millions of people—has seen significant ecological deterioration. The health of aquatic hosts and the life cycles of parasitic organisms are significantly impacted by such environmental variations. In this study, 480 fish specimens from six economically significant species—Labeorohita, Catlacatla, Cirrhinusmrigala, Heteropneustesfossilis, Clariasbatrachus, and Mystustengara—were gathered from four different locations along the Kanpur stretch: Bithoor, Sarsaiya, Jajmau, and Shuklaganj, during four different seasons (pre-monsoon, monsoon, post-monsoon, and winter).

The findings showed that the incidence of nematodes was considerably greater during the monsoon season (68%) compared to the winter season (32%), indicating that temperature and hydrological fluctuations had a substantial impact on the spread of parasites. Geographically, Bithoor had the lowest infection rates, whereas Jajmau, a location known for its organic pollution and tannery effluents, had the greatest infection intensity. Significant positive relationships were found between infection rates and BOD (r = 0.74, p < 0.01) and nitrate (r = 0.66, p < 0.05) according to Pearson correlation analysis, whereas DO exhibited an inverse association (r = –0.59, p < 0.05). These results demonstrate how nematode multiplication and host vulnerability are increased by declining water quality.