Researchers at the University of Surrey in the UK have created a robotic fish that eats plastic waste and powers itself in the process. The invention, nicknamed the robo-fish, was designed with one mission: to fight the growing crisis of microplastic pollution in oceans, rivers, and lakes.
The robot is not powered by batteries like other machines. Instead, it uses a microbial fuel cell that digests microplastics and converts them into energy. In simple words, the more plastic it eats, the more energy it has to keep swimming. This makes it one of the first self-sustaining robots designed specifically for the environment.
The robo-fish first came to life as part of the Natural Robots Contest held by the University of Surrey. Contestants were asked to design a robot inspired by nature that could help the planet. The winning entry came from Eleanor Mackintosh, an undergraduate chemistry student.
“Water pollution, especially plastic pollution, is a huge problem,” Mackintosh told New Atlas in an interview. “It’s not just the ocean that suffers, but also rivers, streams, lakes, and ponds. My design was focused on versatility. What better creature to help clean water than one that already lives in it?”
Her design was selected by a panel of experts and later developed into a real working prototype. Mackintosh explained that she borrowed her inspiration directly from fish, “Fish are adapted to their environment, and gills are an incredible mechanism in nature. They filter oxygen into the bloodstream, so I adapted that design with the purpose of creating a filter for microplastics instead.”
The robo-fish is about half a meter long, similar to the size of a salmon. It swims through the water by flapping its tail, just like a real fish. As it moves forward, it keeps its mouth open, pulling in water. Inside, a cavity collects microplastics while the clean water is pushed back out through gill-like flaps.
When the internal cavity is full, the robot closes its mouth and forces the filtered water out. The gill flaps are covered with a fine mesh that traps plastic but lets water escape. The machine can already capture particles as small as two millimeters.
It is also equipped with small sensors that track light levels and water quality. At night, the robo-fish can glow, which not only looks impressive but also helps researchers monitor its movements.
At the moment, the fish is controlled remotely, but the research team hopes to make future versions more independent. Upcoming models may be able to swim on their own, capture even smaller particles, and travel longer distances.
Plastic pollution is one of the biggest threats facing the planet today. Every year, millions of tons of plastic enter the ocean. Over time, much of it breaks down into microplastics, tiny fragments that are almost impossible to collect.
These particles are now found everywhere in sea salt, in fish and shellfish, and even in human blood and lungs. They can damage cells, disrupt hormones, and spread toxic chemicals through the food chain.
Speaking about the importance of the project, Dr. Robert Siddall, a lecturer at the University of Surrey and creator of the Natural Robots Contest, said, “We don’t know where the vast majority of plastic dumped into our waterways ends up. We hope this robo-fish and its future descendants are the first step in helping us find and control this pollution problem.”
The UK’s robo-fish is not the only attempt to fight microplastic waste. In China, researchers at Sichuan University recently revealed a tiny self-healing robo-fish that attracts microplastics to its surface as it swims. In South Korea, engineers are experimenting with robotic trout that monitor water quality in fish farms. Around the world, scientists are turning to biomimicry, copying nature’s designs to solve environmental challenges.
Still, experts caution that robots alone will not solve the crisis “Technology can help us clean what is already in the water,” Mackintosh said. “But we must also stop adding more plastic in the first place. That requires change at every level of governments, industries, and individuals.”
Dr. Siddall put it, “This is just the beginning. The robo-fish is a symbol of how we can rethink technology not as something that harms the planet, but as something that helps protect it.”
