Google is your buddy. Try searching for mimic filefish, diet.
Here's from wet web media
" <Glad to hear that you're embracing this practice! It will pay dividends down the line!>
So far he has not eaten. I have offered shrimp and salmon at different times. I have read that they also eat algae, and I have some in the QT, but he doesn't seem to eat it. He does rub his mouth on the glass, as if to pick up on microbes (hopefully!), but he does not seem interested in the bigger stuff. I just need to know: 1) what else I should offer; 2) do they have a different primary diet from what I am offering; 3)when should I worry about him not eating, and 3) can you use a better picture for you website, because my guy is a beauty!? Thanks, Rich
<Well, Rich, these fishes will generally eat just about any of the commonly available frozen foods. I'd try some of the Ocean Nutrition foods, such as "Prime Reef", "Brine Shrimp Plus", or even frozen Mysis. These are all eagerly accepted by this species, and offer a good balance of animal and vegetable materials. I Would start to worry if he doesn't eat in about a week...You might try adding some liquid vitamin preparations, like "VitaChem", in his tank water. This may provide some nutrition (as fishes drink water), and may stimulate him to eat. As far as the pic is concerned, why don't you shoot it out to Bob and perhaps he can add it to the collection? Good luck with this fish! Regards, Scott F>"