Heavy Metal Pollution and Its Impact on Fish: A Review on Lead Toxicity

Freshwater ecosystems are increasingly threatened by anthropogenic activities, with heavy metal contamination, particularly Lead (Pb). Lead is a persistent environmental pollutant, that accumulates in aquatic organisms especially fish, which serve as bioindicators of ecosystem health. This review examines the histopathological, biochemical and molecular effects of lead toxicity on fish, focusing on the liver, gills and intestines. Lead exposure disrupts liver function, leading to cellular degeneration, necrosis and oxidative stress. In gills, it induces structural deformities, impairs respiratory efficiency and alters gene expression related to stress and osmoregulation. The intestinal tract suffers from villi degradation, inflammation and compromised nutrient absorption due to enzymatic and genetic disruptions. Additionally, hematological alterations, such as anemia and immune dysregulation, exacerbate systemic toxicity. Understanding these toxicology effects is crucial for assessing environmental pollution and developing mitigation strategies. This review highlights the urgent need for stringent regulatory policies and sustainable environmental practices to minimize lead contamination in aquatic ecosystems and safeguard biodiversity.