HEAVY METAL TOXICITY, BIOACCUMULATION AND OXIDATIVE STRESS IN FRESHWATER FISHES: A SYSTEMATIC REVIEW

Contamination by heavy metals is a significant concern for the environment owing to their cytotoxicity, endurance, biosorption, as well as biomineralization. Our ecosystem may be contaminated by heavy metals from a multitude of both anthropogenic and natural sources. The major anthropogenic sources of heavy metals are commercial, industrial and agricultural processes; the utilization of fossil fuels and gasoline; waste incinerators; mineral extraction; volcanic eruptions; and the degradation of metal-bearing rocks, the use of chemical inputs in tanneries, textiles, and cut flower industries among many other things. These heavy metals mobility into the water bodies affects the physicochemical properties of the water, endangering aquatic species. When a fish consumes food that has accumulated metals, the gastrointestinal organs, outer skin, and gills are indeed the primary entry points for toxic metals. The most frequent heavy metal pollutants that severely damage fish and have an impact on human health include aluminium, cadmium, chromium, nickel, arsenic, copper, mercury, lead, and zinc. These pollutants were also characterized as systemic toxicants. At modest levels of exposure, each of these heavy metals induces organ dysfunction, and the US Environmental Protection Agency and the International Agency for Research on Cancer have characterized them as oncogenic. The key chemical process underlying metal cytotoxicity is the production of peroxidation. Stress impairs regenerative capacity, damages tissues or organs, lowers the immune response, and results in morphological defects. The abundance of protein content found in fish, along with its high vitamin and fatty acid omega-3 content encourages people to eat fish as a main source of nutrients. As a result, built-up toxic substances in fish muscles are easily transferred to human’s biotransformation, where they have adverse effects that hasten the development of many disorders. As a result, it's indeed vital to explore specific causes of toxic metals as well as associated hazardous impact on fish production in order to implement the laws and legislation pertaining to their conservation in the water habitats, as well as to preserve human existence. The explanations addressed in this research are numerous and varied. For such grounds, this study was produced to enhance our knowledge of heavy metals involvement inside the ecosystem, hazardous mechanisms, including detrimental consequences in fishes.