I have some fish in a 40 gal quarantine. I noticed that the flame angel’s rear fin was starting to look a bit frayed and had some discoloration. Then I noticed it had a white spot on it’s body behind it’s left fin, and that fin also had some discoloration. It’s a bigger spot then when I had ich once before and it hangs off it’s body. He seems to be using that fin much less while swimming as well. At first I thought maybe the tangs also in QT were picking on it and biting the fins, but I’ve never seen aggression (one is a tomini and the other is a yellow that is half the FA’s size). But then I noticed the flame’s right eye was a bit cloudy. He also had some stringy white poop today that I hadn’t seen before. I feed mysis and pellets. From doing a little research it sounds like this might be a bacteria issue, but I was looking for some confirmation. None of the other fish have anything wrong with them as far as I can tell. No other medications have been started in that tank, but I was about to start a round of copper for all the inhabitants, but don’t feel comfortable doing so if the flame is already sick. I think the course of treatment recommended is Kanaplex. Is it best to treat the water or food or both? As I mentioned, no other fish show signs of sickness. Is there any harm medicating the other fish in the same tank? I can’t set up another QT. I tried to take pictures, but he’s still very active and camera shy. Ignore the other white dots on the fish as it’s just stuff floating around the water. I circled the only one it has but still hard to see.