I have 3 koi angels, 2 of them look great but one doesn't. It's fins have tiny little white bumps all over them and it's fins look smaller and all raggid. Its on the top, bottom and tail fins, the "arm" fins are fine. My tank is at 80 degrees, the ph is 7 and the kh is 4. I'm not sure about the nitrates/nitritres but I had those tested at the pet store recently and they said they were fine. I tried to take a picture but the angel wouldn't sit still long enough for me to take one. None of my other fish have this, any ideas?