Be very careful with the mantis. I had 3 small ones - less than 2", sneak in with live rocks. They were responsible for me losing several fish, mainly fish that hid in the rocks or gravel where they were easy prey for the mantis. I was going to say clowns would probably be ok, but then my clown I've had for over 4 years disappeared last week and I'd say it was likely the mantis. Don't trust the buggers no matter what size they are.