I have two. They get big and are very heavy polluters. I like them though. Only bottom feeder my crayfish won't mess with. He's tried the cat is to heavily armoured to even be phased. Yes they croak when out of water.
Bought one at Walmart (Blasphemy I know!) Because I felt sorry for the half inch Lil thing. Needless to say he is now 6 inches and has outlasted all my fish and handled many extremes. I believe these guys are bomb proof. Awesome to watch scavenging for food and great with other fish.