The potential of estuarine fishes in supplying micronutrients to coastal and traditional populations in Northeast Brazil

• Estuaries are crucial to sustaining a diverse and rich nutrient source for people. • Estuarine fishes can support balanced diets for traditional groups in Northeast Brazil. • Estuarine fishes can offer high quantities of calcium, omega-3, and selenium. • Conserving estuaries promotes biodiverse and nutritious food for coastal populations. Tropical estuaries are among the most productive ecosystems on Earth, offering multiple ecological and socio-economic benefits for coastal communities. Although previous studies have investigated the value of estuarine resources as human food in Brazil, the potential of fish in providing essential nutrients is still a knowledge gap. Here we investigate the potential nutritional contributions of estuarine fisheries to the diet and food security of local communities. We combined the micronutrient content (calcium, iron, selenium, zinc, and omega-3 fatty acids) of 17 finfish species reported in scientific literature (1994–2025) as caught in Northeastern Brazil estuaries and compared their nutritional content to that of land-based animal proteins (beef, pork, chicken, and ultra-processed meat). We found that, despite species-specific variations in nutrient content, fish have high levels of essential micronutrients. Notably, fish have higher levels of calcium and omega-3 fatty acids, and similar levels of iron, zinc, and selenium compared to land-based animal proteins. These results reinforce the importance of fish in providing not just protein, but also indispensable micronutrients for coastal communities. Considering current threats to estuaries and the nutritional benefits of fish, efforts to protect and restore estuarine habitats are crucial to maintaining this valuable resource.