A Comprehensive Review on the Deleterious Effects of Heavy Metal Bioaccumulation on the Gills and Other Tissues of Freshwater Fishes

Heavy metals can be harmful to aquatic organisms when exposed for a short (acute) or long (chronic) period. They have made a tremendous contribution to human welfare, but they also have considerable negative impacts on organisms that are not their targets. Runoff and groundwater leaching from a range of hazardous metals have a significant risk of contaminating aquatic habitats that pass through industrial or agricultural areas, which could directly threaten freshwater life, especially delicate animals like fish. Fish are the most well-known model for determining the extent of aquatic pollution. Since fish play a significant part in the food chain, the investigation into how toxic metals affect fish might help determine whether or not metals have harmful impacts on human health. This review attempted to consolidate all available scientific findings on the accumulation and uptake of various heavy metals (As, Hg, Cd, Cu, Cr, and Pb) as well as the overall histopathological changes caused by long-term exposure to sublethal doses of these heavy metals on the gills and other tissues of the freshwater fishes. Keeping in mind the above facts, in this review, an effort has been made to elucidate the deleterious impact of metals on the gills of freshwater fishes.