From Diginfonews
If it looks like a fish, swims like a fish, then… it’s a robot fish! With a fuel cell inside, this fish can swim autonomously for about 3 days. Imagine if it can go to the surface to recharge its battery and ingest water to power its fuel cell! Future applications would incorporate a tiny camera in the fish so that it can be used for Search & Rescue and survey operations.
very smart, I like this robot fish which swims like a real fish
http://www.japansugoi.com/wordpress/japanese-robot-fish-from-sedensha/