unless you have them species specific tanks you DONT want to feed them fish. How can they tell feeders from friends?
I have one in my reef along with smallish fish. Right now he could not eat them eventually he might be able to but I want to make him not want to. Thus I feed him PE mysis and that is all he eats. I feed him in the morning a few times week before the lights are on. He will not eat during the day and is afraid of even the clowns when feeding time comes around.
Originally mine did not eat so I bought him 3 peppermints and he ate them. After that it was Mysis or bust so he learned it was food. Now just a few short weeks later he's fat grown quite a bit and is starting to become a bit more bold during the day. He perches and is visable but doesn't move around much. At night and in the morning he is swimming around. However unless he could swallow a fish in one bite I don't see him able to hunt and kill a small fast fish like a wrasse.
Here's a couple pics of mine note the mysis beside.
