Hi there:
I have one as well and it seems to be the same species as Squidd's. My lfs brings them every once in a while and sells them for $35. Mine is about 5 inches long and spends most of its time buried in the sand. When feeding time comes around though he eats absolutely anything that gets close to his mouth. I have him eating krill, squid, prawn and silversides. I also feed him feeders every now and then (saltwater acclimated ghost shrimp and saltwater acclimated Mollies).
He seems to be an ambush predator and basically it is harmless unless you house him with fishes he can swallow. Doesn't move much at all and doesn't bother any other fish. Mine changes colors from very light to very dark and he does it depending on mood and the surface he is on. I really like the fish but it is not for the person that wants a showy, display fish. I would consider the crocodile fishes more of an oddball for an aggressive tank. The only other companions in his tank are a Fu-Manchu lionfish and a Purple Tang.
Hope this helps a little as I am no expert but have had great experience with this crocodile fish.