When Akito Nakadomari first started thinking about fish farms, he noticed something surprising: the machines keeping fish alive were running non-stop, even when they did not need to. Now his research team has found a way to fix that, potentially transforming how the world raises fish.
Fish farms on land, called recirculating aquaculture systems or RAS, reuse water instead of dumping it. This makes them much gentler on rivers and oceans than traditional fish farming. But these systems need constant power for pumps, filters, and aerators — machines that push oxygen into water so fish can breathe. That energy appetite has long been a problem for the industry.
Nakadomari, an assistant professor at Saitama University in Japan, teamed up with researchers at the University of the Ryukyus to attack this problem. They focused on aerators specifically, because these machines use the most electricity in fish farms and are often set to run continuously as a safety precaution.
The trick was finding a smarter way to run aerators without risking the fish. The team studied Malabar grouper, a popular fish in Asian aquaculture. They built a computer model that predicts exactly when oxygen levels in the water will dip too low based on how big the fish are and when they eat. With this model, the researchers could dial aerators up and down at exactly the right moments instead of leaving them on all the time.
The team then connected this model to a system that also manages solar panels, wind turbines, and battery storage. When the sun is shining or the wind is blowing, the system can run the aerators more. When clouds roll in, it knows exactly how much to scale back without endangering the fish. The battery stores extra renewable energy for calm days.
The results, published in May 2026 in the journal Sustainable Energy Technologies and Assessments, were striking. Across a full year of computer simulations, the approach cut electricity use by 17.8 percent and carbon dioxide emissions by 31.9 percent — all while keeping oxygen levels safely above the minimum that fish need. During simulated power outages, the smarter aerator control also helped keep fish alive longer.
Perhaps most surprising, the team discovered that being slightly flexible with oxygen safety margins — allowing tiny fluctuations within safe ranges — opened up huge benefits. Under the conditions they modeled, adjusting the margin by a small amount gave the same energy flexibility as adding five to ten times more battery storage.
"Aerators should not be treated simply as fixed electricity loads," Nakadomari said. "The key is to understand how the process behind electricity demand determines when and how equipment can be operated."
The findings bridge two worlds that rarely talk to each other: power grid engineers and fish farmers. By showing these groups how to speak the same language, the research opens a door to fish farms that are better for the environment and more resilient against outages — all while keeping fish healthy and growing.