I think he's either biting, or it tore on the new hidey rock I got him. When I put it in the tank last night, I didn't realize how close to the glass it was and when I noticed the tear, I checked the rock and in one spot it was super close to the side of the tank, so he might've just got it stuck. I rearranged his tank this evening, took out his old log to make room for the new one now there's plenty of space all over. I felt the inside of the new rock and nothing is sharp, everything has smooth edges, and holes I can fit my thumb through.
Or he's biting. I'm praying it isn't, but it is a little half moon tear on the end of his dorsal. I haven't noticed biting, but I haven't been watching him 100%. Who knows. I really hope he isn't chewing his tail off...Took a while for it to recover from some nasty fin rot, now he's gonna chew it all off again -_-. IF YOU DON'T WANT A TAIL, FINE. BE THAT WAY.