I have one in my tank, not the smartest edition. They are hunters and will eat crabs, snails, and sleeping fish. They are normally sold as being reef safe, but they are not. Sorry, Greg, I don't mean to deter anyone from getting it, just letting them know the possible behavior that may happen. I think they are very cool to look at and to pick out the molted shell/skeleton. It is a perfect replica of the living one, just no guts in it, pretty cool the first couple of times. Mine pretty much stays hidden in my rocks all the time, it may come out at night, but I don't usually see roaming, it just stays in one spot of the tank, very secluded, and a pile of death shells right under its lair. I would say they could maybe be put in with larger type fishes, small ones(at least ones that rest pretty deeply, ie: chromis) ones will tend to disappear one by one. Sorry we didn't see you at Pat's yesterday, hopefully you can make it too the next one, Pat was a very gracious host, I think everyone had a good time.
Matt