I’m looking into getting a QT setup, would a 15g be sufficient and would I need to put all my fish in there?+2
I see ich on the dottyback and probably on the clownfish as well. However, as mentioned, multiple diseases can be at play - I don't see any evidence of Velvet, but I cannot rule out flukes, or Brooklynella (less likely).
Treatment is going to be the real trick here - without a quarantine tank you will be severely limited to what you can try.
Jay