Cadmium and Nickel Contamination in the Kali River and Its Ecotoxicological Impact on Hepatic and Hematological Health of Channa punctatus (Bloch.)

Abstract

Cadmium and nickel contamination in freshwater ecosystems has become a significant environmental issue, mainly because these metals stick around for a long time, accumulate in living organisms, and can be toxic to aquatic life. The Kali River in western Uttar Pradesh, India, is particularly affected, receiving a mix of industrial, agricultural, and municipal waste that raises the levels of these metals. This review pulls together existing research on where these metals come from, how they spread, and their harmful effects on Channa punctatus, a fish often used as a bioindicator. It highlights how these metals accumulate in the fish, the oxidative stress they cause in the liver, and the changes in blood health due to exposure. Cadmium and nickel can mess with the fish's antioxidant defenses, increase harmful reactive oxygen species, and lead to liver damage, while also causing anemia and weakening the immune system. These health issues pose risks not just to the fish but also to the stability of their populations and the overall health of the ecosystem. Plus, the accumulation of these metals in edible fish tissues raises concerns for human consumers. The review emphasizes the need to include biochemical and hematological markers in regular monitoring to better understand heavy metal pollution and improve river management strategies.