Robotic fish have been created, and they are working together. Robofish are underwater robots that can,
co-operatively track moving targets underwater, such as groups of whales or spreading plumes of pollution, or explore caves, underneath ice-covered waters, or in dangerous environments where surfacing might not be possible.
The roughly 10 pound salmon-sized devices have fins and propellers to allow movement in water, and they are built to simulate real fish. The intent is to generate bio-inspired systems that perform better than existing engineered systems.
The ideal of using nature inspired solutions and models in order to make robotics work more efficiently in our world makes a lot of since to me, since Nature has done a lot of refinement over the years free for the sampling.