Trained Fish

It's true, you can train most anything with positive reinforcement.

Trained gold fish
http://www.youtube.com/watch?v=Ze-2Z7Wh1nQ

Jumping Fish
http://www.youtube.com/watch?v=jEI8lMnLI_k

Trained fish in AXE commercial.
http://www.youtube.com/watch?v=jEI8lMnLI_k

Clicker type training a fish with a light
http://www.youtube.com/watch?v=STLgWyXGUMg

Target Training with Fish
http://www.youtube.com/watch?v=bVdTpP3tQKk