I read an article called "How do you train a fish?" about possible solutions to the ecologically unfriendly fish farming methods in use at the moment. You can read it here: http://news.bbc.co.uk/1/hi/sci/tech/8283701.stm
Its basically about how you can train sea bass to respond to a frequency played in the water to make them swim to a certain point. I thought the robotic shark bit was pretty interesting too.