Chemical contaminants and fish: implications for health and ecosystem sustainability.

Chemical pollutants in aquatic ecosystems pose a significant and growing threat to fish health and overall ecosystem sustainability. This review highlights recent findings on the ecotoxicological effects of major aquatic contaminants, including industrial effluents often containing heavy metals (HMs) along with agrochemicals, pharmaceuticals, and personal-care products (PPCPs) on fish species. Particular emphasis is placed on the underlying mechanisms of toxicity, such as immunotoxicity, which increases susceptibility to infections, and neurotoxicity, which alters behavior and predator avoidance, ultimately reducing fish survival. In addition, emerging contaminants, including microplastics and nanomaterial residues, are critically examined due to their potential role in biodiversity loss and ecosystem instability. The review also discusses advanced assessment tools, such as biomarker-based approaches, omics technologies, machine learning models, and high-throughput screening techniques, which provide innovative strategies for evaluating and mitigating toxicological impacts. By integrating interdisciplinary perspectives, this review provides a comprehensive framework to support regulatory policies and promote sustainable management practices aimed at protecting aquatic biodiversity and maintaining ecosystem health.