oh some information to pass on... there are two types that commonly are called clown gobies. There is the Gobiodon citrinus "citron/clown gobie" and the Gobiodon okinawae "yellow coral gobie" ***** to correct me from my last post I do not have the clown I have the yellow coral I is the one that J&L calls the yellow clown *****. At the bottom there are two links to images of the two types. I have searched to find out if one of the two types will tend to eat acros more then the other. But I have not found any article with that kind of information. I do know that they both like meaty foods. Could it be possible that they nip at acros to make the nest?
Yellow coral
Citron