That's a fish in trouble, either roughed up from bullying or suffering serious stress-- again, probably from bullying. Quite often you don't see the agression because it happens at night or when you're not in the room.
Either way, if it was my fish I'd get it right out of there for recovery, likely for treatment, or you're going to lose it. I learned that lesson years ago. Once I learned to recognize the signs and act fast, I saved fish I would have once lost and not understood the reason why a once healthy fish suddenly became 'sick'.
There's a significant difference between these pictures and your last post. What often happens next is the fish stops eating, starts hiding or hanging in a corner, before long it develops a fungus and/or cloudy eyes, etc. It can happen fast once a fish starts looking like yours does if nothing is done to remedy the situation.
