Have these lyretail anthias in quarantine for about 3 weeks now. All seemed fine for the entire time. Last few days, one of the three fish started to lose its color and it now has this rash looking mark on its side. QT is a fresh setup, these are the only fish in the QT tank. During acclimation on the first day, I did a formalin dip, and once I got the fish eating I did one course of Prazipro. No other treatment so far, and that was a few weeks ago at this point. The fish is definitely hiding, but comes out to eat, and otherwise seems to be ok (ie, no heavy breathing, etc.). The fish is currently eating. can you please help identify what this is, and how to treat? See attached photos.