A breakthrough study suggests that the aquaculture industry—long criticized for its environmental toll—could become a powerful ally in the fight against climate change. Researchers have found that a simple yet surprising technique—adding iron ore to fish farming waters—could cut global carbon dioxide emissions by millions of tons annually. Published in Nature Food, the study opens the door to what scientists are calling aquaculture carbon capture, a process that may revolutionize sustainable fish production.
The global aquaculture industry, which supplies over half of the world’s seafood, is facing increasing scrutiny for its environmental footprint. In addition to greenhouse gas emissions, fish farms often struggle with waste management and water pollution. One of the most dangerous byproducts is hydrogen sulfide, a toxic gas generated when bacteria break down organic waste like uneaten food and fish excrement in low-oxygen environments—common conditions beneath floating fish pens. Hydrogen sulfide is lethal to fish even in small amounts and poses risks to nearby marine life and ecosystems. Traditional solutions are costly and often fail to fully address the issue.
Iron ore offers a promising alternative. According to the study led by Dr. Mojtaba Fakhraee, a postdoctoral researcher at Yale University, iron ore reacts with hydrogen sulfide to form a harmless compound called iron sulfide. This not only neutralizes the toxic gas but also increases water alkalinity. Alkaline waters have a greater capacity to absorb carbon dioxide from the atmosphere, effectively turning fish farms into natural carbon sinks.
Using advanced computer modeling, the research team assessed how this reaction could play out across various countries and environmental conditions. The results are striking: in China, the world’s largest aquaculture producer, this method could capture up to 100 million tons of CO₂ annually—comparable to the yearly emissions of around 21 million cars. If extended to other major aquaculture producers like India, Indonesia, and Vietnam, the total annual carbon capture could reach between 25 and 140 million tons.
Each hectare of treated fish farm could sequester between 2 and 10 tons of carbon per year, depending on local variables like temperature, salinity, and organic waste levels. This level of capture could offset between 50% and 100% of emissions currently produced by the aquaculture sector, potentially transforming it into a climate-positive industry.
In addition to reducing greenhouse gases, this technique offers practical ecological and economic benefits. By removing hydrogen sulfide, it significantly lowers fish mortality rates, improving animal welfare and boosting farm productivity. Healthier fish also mean lower dependency on antibiotics and other interventions, enhancing the overall sustainability of operations.
Iron ore is abundant and inexpensive, making the approach financially viable even in lower-income regions where aquaculture is a key source of food and employment. This makes it not only an environmentally sound strategy but also an accessible one.
Although the findings are promising, real-world application will require further investigation. Future studies will need to explore optimal iron ore types, application methods, environmental safety, and integration into existing aquaculture systems. Field trials and collaborative programs between researchers, policymakers, and industry players will be essential to turning this concept into practice.
According to Dr. Fakhraee, “We’re not just looking at a way to fix a pollution problem—we’re looking at a scalable, cost-effective strategy that could make fish farming part of the solution to climate change.”
As global demand for seafood continues to grow, especially as populations rise and dietary preferences shift, this method could mark a turning point for aquaculture. If successfully implemented, aquaculture carbon capture could become one of the most innovative and impactful tools for climate mitigation within the global food system.
