Robo-Carp!

This is fairly awesome...it's fairly old, but I hadn't seen it before.

http://news.nationalgeographic.com/news/2005/10/1007_051007_robot_fish.html

From National Geographic:

October 7, 2005—This week the London Aquarium unveiled the newest "species" to join its collection: robo-carp.

Computer scientists at the University of Essex in the U.K. developed the self-guided robot fish, seen here swimming in the aquarium. The designers say it is the smartest such robot yet created—the fish uses artificial intelligence and built-in sensors to avoid obstacles and respond to environmental changes.

The fish's battery lasts for up to five hours, though the scientists hope to one day program it to search for and access a recharging station when it runs low.

"This work has many real-world applications, including seabed exploration, detecting leaks in oil pipelines, mine countermeasures, and improving the performance of underwater vehicles," project leader Huosheng Hu told the Associated Press.

The bot, which resembles a one-and-a-half-foot-long (half-meter-long) common carp, mimics the undulating motions of a real fish swimming and turning. Three of the cyber-fish will swim in a tank at the aquarium alongside their living counterparts.

—Victoria Gilman