If you want to learn more about the behavior of a school of fish, why not just build a robot fish to lead them? That's what two engineers from the New York Polytechnic Institute though, and the robot fish showed a surprising aptitude for leadership. In a test, the researchers placed the robot fish in an artificial channel of water meant to simulate a river, along with some live golden shiner fish. Initially, the shiners ignored the robot fish, but when the robot moved in a particular way that was similar to the way the shiner fish swim, the fish would line up and follow the robot. The live fish also slowed their movements when in formation behind the robot, indicating that there was an energy advantage to be gained by swimming in a school.
The researchers were a bit surprised that the live fish accepted the robot so readily — especially considering it was twice as large as most real fish. There was also a question as to why the fish accepted a robot not only as a member of the school but as a leader. Despite these questions, the researchers believe that a robot fish could be used to help lead fish populations in danger of environmental disaster — the design will probably need some tweaking before that becomes possible, however.