I've spent the last 20+ minutes looking at youtube videos of these guys. Check out the setup in this video: it looks like a full aquarium with community fish and I would guess some form of amphibian or turtle judging from the turtle dock. If you don't want to be bored, fast forward to around the 1:20 mark; It's like a sarlac but different.

Pretty interesting snakes IMHO.

http://www.youtube.com/watch?v=7egLyelwXOE