The picture is a little cloudy on my comp. so it's hard to tell how deep it is. My arowana is constantly hitting his mouth on the top of the tank when he's goin for food. As long as your water quality is in good shape it should heal in a few days or atleast start to heal depending how deep it is. I'd suggest re-adjusting the log though, so that he dosen't have to use his head to push it up to get under it.