My painted angler is very reef friendly. If you have any frags or anything in your tank you don't want knocked over, then glue it down. He will walk all over your tank. Not swim either, I said walk haha. I have a hermits in my system as well largest is about a 1.5" shell. I have never saw my angler make any motion towards any crabs or snails. Since I've had my angler he has eaten on his own: 3 green chromis, two damsels, and maybe 7 peppermint shrimp. Even if you feed your angler everyday he will still eat anything he can fit in his mouth that comes into his eating area. If you can handle an angler potentially eating your fish, it's deffinately worth it to have in your tank