Actually, I was faced with a similar situation. My big blood parrot got a huge scrape on the side of his face. It was white and kind of dangling like I see in yours. It took 3-4 weeks to heal, but each day I saw improvement. It ended up covering over white, looking like scar tissue and I thought I would have a fish with a white spot but over the next few months, the scales came back correctly colored. Since it is a rainbowfish and since they come from ultra-clean mountain streams, more than a 25% water change will do. With rainbowfish, the norm is 50% once a week. I think maybe a week of antibiotics, but then go for something like melafix or stress coat, something mild for growing tissue. Boesemani, for some reason, freak out faster than most rainbows, and are very nervous fish compaired to other rainbows. They need to be given the "spa" treatment. Clean water, frequent water changes will help it heal better than anything you can give it. By the way, I did not put any thing in the blood parrot, except water changes. Oh and try to find out what got him going in the first place. They are very frightened by bright lights and will hide before fighting.
