A lot of people here recommend to make a custom blender mush, and I'm sure someone here can advice you how to make one, or you can search for it.
I feed mine either Cyclopeeze or flake food every other day and they seem just fine. They go after the cyclopeeze like it's liquid crack.
I know of a few instances where people have gone out and purchased anenome's, and the clowns don't even bother with 'em.
This can be true and often the clowns have to be matched to the right anemone.