Royal Gramma ich?
 

Had a royal gramma in QT for 4 weeks and never showed signs of ich. Went into main display over 2 months ago. Had to remove a falco hawk that was to aggressive towards gramma and ended up splitting the upper part of the grammas tail. It has since healed. But I noticed these spot on upper part of tail only not anywhere else and they have been there for at least 7 days. The gramma is NOT showing symptoms of a parasite by flashing etc. You really have to look hard with your face planted up against glass to see. Have a UV running and don't want to medicate. It is a reef tank and most meds don't work and just end up spiking your nitrates. I know what ich looks like and just want others opinions of what it might be. Can't pull gramma out to treat in QT with 50+ pounds of live rock and corals to work around in a 40 breeder not going to do it. I do want to be able to add more fish. Right now the gramma is only fish in the display tank. Thoughts appreciated.

The story and timeline supports ich. Likely the Gramma had it all along but had acquired enough immunity to keep it in check. The stress of being chased then lowered its immune response and caused the ich to show.

I caught two of my Gramma with a barbless micro hook and the last that escaped and then smartened up with a trap.