I got this majestic angle a couple of weeks ago. I noticed when I got him home that he had a small scratch on his side. Over time, it looks like the scratch is getting bigger, and white stuff is comming out of it. Also, his fins next to the scratch look worn out and he looks like he is trying to itch it.
My water parameters look fine (8-8.2PH, 0 amonia, 0 nitrites, 20ppm nitrates and 1.023 SG, 80 deg temp) I've been using malafix and primafix based on mike at austin aquariums recomendation, but it doesn't look like its helping. here are a couple of photos (this guy moves too fast for my macro zoom, so they are not the best quality):

https://webspace.utexas.edu/eleyan/tank/majestic02.JPG
https://webspace.utexas.edu/eleyan/tank/majestic03.JPG

What do you recomend for treatment?