I just got some frags in yesterday. And one of them was an acan. I have a filefish but I have been watching him hard because if he disides to turn on my acan it's just a small frag. I have seen him bite it once. It did not cause any damage. My question is I went to sleep and I saw a head of the acan look like this, and I'm wondering if that's a bite mark. I can't remember if it had that yesterday. It's the little hole on the left of the closest head.