Robot fish a cunning spy

The sea drone is 1.5m long and weighs 45kg. It is expected to one day carry cameras and other naval equipment. Photo / Thinkstock

The US Navy is working on a robotic fish that will be able to swim undetected into hostile waters and send back information on opponents' ships.

Project Silent Nemo is under way at a military base outside Washington and navy scientists hope to deploy the robot into the field next year, according to Pilot Online.

The robot fish looks startlingly like a blue fin tuna from a distance and it is almost impossible to tell from its black dorsal fin that it is made of gears and whirring cogs.

The sea drone is 1.5m long and weighs 45kg. It is expected to one day carry cameras and other naval equipment.

Controllers can guide the robot with a video game-style joystick but it can also be programmed to follow a set course.

The navy hopes to use it for tasks that would be dangerous for a human diver, such as detecting mines and inspecting damage to the hulls of US warships.

Silent Nemo is powered by the movement of its own body rather than propellers, making it far quieter than a miniature submarine and harder to track with sonar.

"This is an attempt to take thousands of years of evolution and try to incorporate that into a mechanical device," said Captain Jerry Lademan, who has been working on the project.