NYU-Poly's Dynamical Systems Laboratory, using the scientific thinking of Dr. Maurizio Porfiri, have been studying how schools of fish interact with an artificial "dominant" fish. The work is partly for the sheer scientific curiosity, but also because of interest in how wild fish may be directed through the ocean to protect them from straying into hazardous locations in a more natural way than building nets or barriers.
Porfiri's studies involved a tank, some golden shiner fish, and a robotic fish that he's built. Though this fish is merely able to swim about in two dimensions and can't dive or surface like a real one, it's no clockwork bath toy by any means. Porfiri's research is based on the fact that fish of different species often flock together in huge schools, each species with different colors and sizes--because of this trait he realized fish may accept a totally artificial fish swimming among them, and even accept it as a leader if it were bigger than them. But the artificial fish had to be acceptable as a real-enough fake, so it was designed to be biomimetic, with ionic polymer motors that shrink and swell when an electrical charge is applied so they work almost like real muscle. As a result, the robofish swims very realistically.
Though much more modeling and experimentation is needed, for example with a robot fish that can also swim up and down, Porfiri's research has already indicated that fish schools can be steered by a robot leader. And this means that where sea-based turbine power generation systems are installed, it may be possible one day to divert fish away from the danger by having a team of robot life-saver fish ready to help.