Hello, so I'm 3 days into quarentine on my angel with suspected velvet. Treating with copper. He's doing better, the white spots over the eyes have disappeared. But now I am seeing a little bit of a coating on the clown on top in the photo in the main tank. The thing is, I think it's been in my main tank for months and my fish were immune to a point. Recent stress from a few new tank mate attempts sent angel over the top though. He had the yellowish coating for a long time (months) but only recently began scratching and letting the shrimp clean his gills. That's when I also noticed the white over his eyes, respiratory distress and began to investigate the pathogen and treatment options. So my question is : is it possible that my fish are going to be OK and are possibly immune in my main tank? Or are they likely to all get infected and die? I just can't decide who and when to take to the hospital tank. I feel like it's a death sentence. Even though angel is hanging strong. From the reading it sounds like velvet is almost always so quick to kill, but my case seems odd. Long and drawn out with a lot of hopeful thinking. This is very stressful and depressing for me and my fishy friends. Please help me diagnose and decide when to treat what needs to be treated.