I have three Koi, 4 bala, 6 mollies, and a blue crawfish in my tank. A couple of days ago I noticed the mollies where biting at one of my koi. So I decided to remove the mollies to another tank by themselves. But yesterday when I was feeding the Koi, I noticed the one they were biting has this white haze on his head now. I don't know if the mollies were biting him because he was sick, or if he has the white haze because the mollies irritated his skin. Any idea what I should do? I love him and want him to live.