This morning I wake up to see two of my skirt tetras chasing One-eye, another skirt tetra who has the unfortunate blessing of being cyclopian (not my fault, was like that when I got him). They are chasing him to the point where the two chasers are showing stress and One-eye is basically laying there and taking it from them. I separated the fish from each other for a while and then put them back in because I had to go to work. I come home today and they are all back to normal, not showing any stress, but One-eye has what appears to be a small bite/scrape on his forehead. Any idea what could have caused this? The rest of the fish in the tank are fine, water params are good. I don't want to wake up tomorrow to another fish fight.