Robot fish can lead real fish in a closed environment, particularly if it helps them save energy. This is the finding of engineers from New York’s Polytechnic Institute. There's nothing fishy about the following video.
(Robot fish lead, real fish follow)
Very little is known about the mechanism involved when fish form schools, other than that they likely do it to make mating easier, to conserve energy and to ward off predators. All of these activities are offset by the increased competition for food and the problems associated with communicable diseases. To help understand what causes fish to form a school, Stefano Marras and Maurizio Porfiri built a small robotic fish that they attached to the bottom of an artificial channel of moving water in their lab. They then placed a live golden shiner fish in the water behind it to see what would happen (because the water was moving the fish had to swim just to stay even.) They found that if the robot fish didn’t move at all, the live fish tended to ignore it. But if they caused the tail on the robot fish to move in a way that is very similar to the way golden shiners move theirs, the live fish would move into formation behind it. And that wasn’t all, after moving into formation, the real fish slowed its movements slightly, indicating that by following the robot fish, it was gaining an energy advantage similar to the way geese do when they form a vee when flying.
In his 2002 story Slow Life, science fiction author Michael Swanwick wrote about robot fish that help explore distant worlds:
The Mitsubishi turbot wriggled, as if alive. With one fluid motion, it surged forward, plunged, and was gone.
Lizzie switched over to the fishcam.
Black liquid flashed past the turbot’s infrared eyes.
Straight away from the shore it swam, seeing nothing but flecks of paraffin, ice, and other suspended particulates...
(Read more about the Mitsubishi turbofish)