Tetra has huge chunk out of body! Pic included!

TallTree01 Member Posts: 580
One of my flame tetras appears to have been brutally mauled at some point. There is a chunk across almost half his body exposing his insides. Bullying between him and his other tetras seems unlikely as he's always been the biggest baddest alpha. I don't know whether to seperate him to another tank or not?
Here are pictures ( warning: graphic )
photo image_zps10kteym5.jpg
photo image_zpsr4xqxyqs.jpg

It doesn't appear to be infected and he seems totally ok with it and is playing with his mates. I don't think it was bitten from him he must have whacked it on a rock or something. Please advise!!