Iron is a vital element for numerous physiological processes in various organisms, but when present in excessive amounts, it can lead to hazardous effects. The present study aimed to examine the levels of iron (Fe) in the coastal swamp ecosystem of Kuala Tambangan in South Kalimantan. The sea catfish (Arius sagor) was employed as an indicator species to assess the extent of heavy metal pollution in the area. Insights into the effects of Fe levels on both environmental and human health was obtained by the analysis of Fe levels in water bodies and fish tissues. The Fe levels in the coastal swamp environment of Kuala Tambangan were assessed using atomic absorption spectroscopy. The results revealed a significant and positive correlation between the levels of Fe in both water and fish tissues. Both natural and anthropogenic causes contribute to the accumulation of Fe, with anthropogenic pollution being the primary factor. The research findings indicated elevated levels of Fe throughout the coastal swamp ecosystem of Kuala Tambangan, prompting worries over potential ramifications for both ecological and human health. The results of this study would provide valuable insights that can enhance our comprehension of more effective approaches to managing coastal swamp wetland ecosystems. Continuous biomonitoring, identification of pollutant sources, public awareness, regulatory enforcement, and remediation are essential to address heavy metal pollution and its ecological impacts.