My blue hippo had a bad case when I first got him - after stressing me like crazy and lots of research, it boiled down to if I did nothing he would work through it. I have about 12 fish in a 75g, and no one else ever got it.
Worse was when my hydrometer (ya, I have a refractometer now) led me to up my salt to 1.035....man, he was a mess, even on his eyes. I didn't do anything except keep the water good (after slowly getting the salinity back in line) and he's been clean for over a year.