Bioaccumulation and Toxicological Effects of Heavy Metals in Major Freshwater Fish Species of the Ganga–Yamuna Basin, Uttar Pradesh

Abstract

Heavy metal contamination has emerged as a major ecological and public health concern in freshwater ecosystems worldwide, particularly in densely populated river basins such as the Ganga–Yamuna system in Uttar Pradesh, India. Rapid industrialization, population growth, agricultural intensification, and continuous discharge of untreated effluents have significantly increased the concentration of toxic metals including lead (Pb), cadmium (Cd), chromium (Cr), mercury (Hg), copper (Cu), and nickel (Ni) in aquatic environments. These metals are persistent, non-biodegradable, and capable of accumulating in aquatic organisms, especially fish, through direct absorption from water, ingestion of contaminated food, and sediment interaction. Scientific investigations demonstrate distinct tissue-wise bioaccumulation patterns, with highest concentrations generally reported in liver tissues followed by gills and muscles, indicating detoxification stress and respiratory exposure pathways. Heavy metal exposure results in oxidative stress, enzymatic disruption, histopathological damage, immunological suppression, reproductive impairment, and altered behavioral responses in fish species, ultimately affecting survival and ecosystem balance. Furthermore, dietary intake of contaminated fish poses potential long-term health risks to human populations dependent on riverine fisheries. This paper presents a comprehensive academic review of heavy metal bioaccumulation trends and associated toxicological effects in major freshwater fish species of the Ganga–Yamuna basin, integrating ecological, toxicological, and public health perspectives while emphasizing the need for sustainable river management, strict pollution regulation, and long-term ecological monitoring strategies.