I have one of these in my tank too. I haven't seen him bother any of the inverts, but what is weird is that I can't say I've ever seen him eat either (I've had him about a month to 6 weeks). If I put frozen food in the tank, he gets excited and swims around, but I don't actually see him take any bigger pieces of food (he has no interest in pellets at all). I've tried brine, mysis, 50/50 - nothing. So, unless he's filter feeding, or eating other things in the tank at night when I can't see him, I'm not sure he's eating anything.
But, if he wasn't eating anything, I would have thought he would have demised by now. A normal fish can't go 6 weeks without eating before going belly up, can it?
Otherwise, it behaves "normally".