Mercury (Hg) induced toxicity in freshwater fish: A comprehensive review

various forms, methylmercury (MeHg) is the most toxic, highly bioavailable, and prone to bioaccumulation. Exposure to mercury alters antioxidant enzyme function, elevates lipid peroxidation, and disrupts metabolic processes, ultimately impairing growth and immunity. At the behavioural level, affected fish display changes in locomotion, feeding, predator evasion, and reproductive activity. Histopathological investigations reveal significant tissue damage in the gills, liver, kidney, and gonads, compromising organ functionality. Additionally, mercury interferes with endocrine regulation, causing hormonal imbalance, reduced gamete quality, diminished fertility, and abnormalities in offspring development. Collectively, these toxic effects threaten individual health, population stability, and ecosystem resilience. Current studies (2020–2025) emphasize the urgent need for systematic monitoring of mercury contamination and mechanistic understanding of its toxic impacts to safeguard freshwater biodiversity.