Robofish on a mission to clean up the Thames

Researchers at the University of Essex in Colchester are working on the robofish as part of a £2.5million EU-funded project to find new ways of monitoring water waste.

Each fish will be about 50cm long, 15cm high and 12cm wide. They will be packed with pollution sensors that can electronically "sniff" harmful chemicals in the water. Scientists have developed "swarm intelligence techniques" which allow the fish to work as a team without humans.

The robots will communicate with each other using wi-fi as they seek out areas of pollution. They work out where they are with inbuilt GPS systems - in effect, mini satnavs - and artificial intelligence software will enable them to move without the need for a human operator: they will only alert staff if pollutants are found.

A fish that finds contamination sends GPS coordinates of the location to others. "Each school will contain five fish, and they will constantly monitor for pollutants," said Dr Dongbing Gu, who is leading the research. "When they find something, they will send a message to the rest of the school, who will then converge on the area to take readings."

The fish move by undulating their bodies - propelled by motors - and use fins and a tail to change direction. It is hoped they will travel at speeds of up to half a metre per second.

Working prototypes could be available within 18 months. Different sensors will be fitted to hunt for different pollutants. The data could be used to build a "real time" 3D map of pollutants in the water, allowing operators to determine the best way to clean up the area.

The fish will initially be used in ports to monitor emissions and leaks from large ships, but Dr Gu said the same system could be used in the Thames. Researchers hope the robots will be able to spend up to 24 hours in the water before needing to be recharged.

They will be based on a design for robot fish that appeared as visitor attractions at the London Aquarium, swimming alongside living creatures.

Rory Doyle, from engineering firm BMT Group, which is overseeing the project, said: "This might look like something straight out of science fiction [but] there are very practical reasons for choosing this form.

"In using robotic fish we are building on a design created by hundreds of millions of years' worth of evolution which is incredibly energy efficient."