I was at king ed pet the other day and know exactly which one you're talking about, i don't have any filefish, but was reading about that species, the orangespotted filefish that is, and from what i've read its often mistaken with the longnose filefish who only eats coral polyps, however the names are interchangeable within that species so choose carefully -heres a link for the one that exclusively eats coral polyps (acro's especially) >>
http://www.marinecenter.com/fish/fil...ottedfilefish/