I vaguely remember having an aquapet a few years back. I remember having a difficult time getting it to go to sleep when I wanted to stop playing with it. Basically, after not hearing any noise they would call for attention a few times then go quiet. I would have to leave it alone with it's microphone and speakers taped to get it to sleep. As I recall, they're also very, very noisy.
The new ones a then the olones. They have two games on them, they sing, alot... Most of the characters returned I think... Not 100% on that though. They turn off a bit easier and the container is an aquadrop shape. Fun to play with, not to eat... Lol. Kidding. But they are more entertaining then the ones that came out a while ago.
I had one of those, and they're really annoying. They constantly beep and it drove me to the point of insanity so I smashed it in my yard and buried it in the soil. No idea if it's still there. *goes and checks*