i had trouble with my volitan lionfish i recently got. he refused to go near any frozen food including the silversides that my LFS told me to feed him with. I bought a bunch of white cloud minnows (live) and he jumped all over them!
Why is live food out of the question? it may be your only choice at this point. I have yet to get mine to take anything other than live fish, i've actually been harvesting the young from my african cichlid tank to feed him
