Author(s): Tushar Pandey, Akash Jayasval and Anand Kumar

Abstract: Manganese (Mn) is a vital trace element required for several physiological functions in fish, namely enzyme activity, bone growth, and antioxidant defense. However, with increasing human activities like as mining, industrial release, and the usage of Mn-based agricultural chemicals, aquatic environments are experiencing unprecedented Mn pollution. This high ambient Mn provides a considerable hazard to aquatic life, particularly fish, by surpassing homeostatic thresholds and causing a variety of harmful consequences. The review's central focus is a comprehensive examination of the multidimensional aspect of Mn toxicity, based on previous research publications. It examines the short term and long-term toxic levels of numerous fish species, emphasizing significant species- and life-stage-specific sensitivity. It fully details Mn-induced behavioral changes, such as decreased swimming ability, abnormal feeding and predator avoidance behaviors, and disturbed social relationships. The biochemical changes are investigated, with an emphasis on oxidative stress as the primary form of toxicity, in which Mn disrupts the pro-oxidant and antioxidant balance, resulting in peroxidation of lipids, protein carbonylation, and damage to DNA, especially in metabolically engaged tissues such as the gill, liver, and brain. Hematological characteristics are reviewed, indicating magnesium-induced anaemia, leukocyte abnormalities, and reduced oxygen transport ability. Histopathological examinations reveal extensive destruction to the gill epithelium, hepatic tissues, and renal tubules, which impairs respiration, metabolic processes, and osmoregulation. Furthermore, the study brings together evidence of Mn-triggered genotoxicity, such as chromosomal abnormalities and DNA strand fragmentation, which represent long-term dangers to the population. The tables provide a comprehensive reference on toxicity thresholds, behavioral, biochemical, hematological, histopathological and genetically toxic endpoints across species. The finding highlights that oxidative stress is a key, unifying process in the complicated, multi-organ phenomena of Mn poisoning. It highlights important knowledge gaps, including the need to develop reliable biomarkers for proactive monitoring, relationships with additional environmental stressors (such as low pH and hypoxia), and long-term transgenerational consequences. In light of rising Mn pollution, this study emphasizes the need for strict regulations and additional research to protect fish populations and the health of aquatic ecosystems.

DOI: 10.22271/fish.2025.v13.i6c.3198

Pages: 242-250  |  165 Views  105 Downloads

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