i have one it nibbles on it but doesnt really chow it down have noticed him nibbling on my brain once didnt hurt it though, someone told me they can be there a long time before eating it if at all. it also has to be a matted filefish as he is the least likely to eat other corals.you can try getting a nudi branch they are supposed to be quite effective but will starve when he eats it all up. if he cleans your tank right out give him to someone else so he doesnt starve.not sure how hard they are to keep alive as i have never had a nudibranch,hope this helps
