A review on heavy metal-induced toxicity in fishes: Bioaccumulation, antioxidant defense system, histopathological manifestations, and transcriptional profiling of genes

Aim: This review provides information about heavy metal occurrence in the environment, destructive mechanisms, and lethal effects on fish. Summary: Heavy metals (HMs) are one of the major causes of environmental contamination globally. The advancement of industries has led to the emanation of toxic substances into the environment. HMs are stable, imperishable compounds and can accumulate in different fish organs when they reach the aquatic regimes. The most ubiquitous HMs are chromium, arsenic, mercury, cadmium, lead, copper, and nickel which can pollute the environment and affect the physiology of fishes. Accumulation of metals in the fish organs causes structural lesions and functional disturbances. Contamination of heavy metals induces oxidative stress, histopathological manifestations, and altered transcriptional gene regulation in the exposed fishes. Conclusion: Heavy metal bioaccumulation leads to different anomalies in the non-target species. Metal toxicity may cause aquatic organisms to exhibit cellular dysfunction and disturb ecological equilibrium.