It does look to be a little frayed. No sharp decorations or strong filter intake?
If those aren't present, then it's a good bet that it is tail biting. If that is the case, feed him throughout the day if possible (So if he eats 6 pellets a day, feed him 3-6 times to keep him occupied) and give him things to mess with, like bottle caps and ping pong balls. Also, change around his tank every so often during a water change to make it new to him and put different things for him to look at outside of his tank.