Carbon capture on fish farms can combat climate change while removing toxic sulfides

According to a recent study published in Natural food.

Lead researcher Mojtaba Fakhraee, an assistant professor of earth sciences who will take up her position in August 2025, says traditional methods of reducing emissions are no longer enough to keep global temperature rise below 2°C, a objective set by the Paris Agreement.

In recent years, scientists have turned their attention to carbon capture, the process of capturing CO₂ emissions from industrial sources – as a possible solution to combat climate change alongside traditional efforts to reduce carbon emissions.

Fakhraee, in collaboration with Noah Planavsky, professor of earth and planetary sciences at Yale University, developed a model to explore how alkalinity production through increased iron sulfide formation in fish farms and other Low-oxygen aquatic environments could offer an efficient and inexpensive way to capture at least 100 million tonnes of CO₂ annually.

“We are currently in the situation where to be able to maintain this threshold of 1.5°, we would have to remove carbon from the atmosphere,” explains Fakhraee. “There’s no way around this.”

Fakhraee says the study focuses on fish farms because they are directly influenced by human activities and can be an ideal place to capture carbon while reducing concentrations of toxic sulfides.

The researchers’ model found that adding iron, which reacts with accumulated hydrogen sulfide, increases alkalinity. This, in turn, increases carbonate saturation levels, thereby improving CO capture.₂ of the environment.

This model would be most effective in countries like China and Indonesia, which have abundant fish farms, the authors note. Fakhraee and Planavsky estimate that China alone could eliminate nearly 100 million tonnes of CO₂ per year from the atmosphere.

Fakhraee says this discovery will also have a positive impact on the success of fish farms, as the buildup of hydrogen sulfide can be toxic to fish, leading to increased mortality rates or fish being too sick to sell. The proposed model would reduce this toxicity, leading to larger fish populations and more sustainable and profitable operations.

He added that this approach could be more effective than other carbon capture methods because it would essentially store the carbon permanently.

“It will be stored on a time scale of several thousand years, which is much longer than the lifespan of CO₂ in the atmosphere,” he said.

Fakhraee says this is just one approach to carbon capture. However, if put into practice, it could have a significant impact on carbon emissions from fish farms.

“This is just one possible pathway to capturing carbon at a meaningful scale,” he says. “The co-benefit of this specific pathway is that it would help neutralize carbon emissions from fish farms, resulting in a more sustainable fish farming industry.”