This Blood Parrot fish rolls the contraption around just by swimming around in its bowl. The sensors and the onboard computer detects which direction the fish is swimming in, then directs the wheels accordingly.

If you ask me, this is a dangerous precedence. First we help fish roll around on land, next we're going to teach monkeys how to fly and use firearms. Why don't we just hand over the keys to our civilization already?

Terranaut - Fish Explore Land With Robotic Vehicle [Technovelgy]