If the fish is eating, acting normal, and not flashing, I would wait it out. If it gets at all worse, then rethink things. When I moved, and upgraded my reef, the fish broke out VERY badly with ich (I knew my tank was never ich free). At one point the powder blue had skin texture like he was dried and salted
BUT... he never once flashed, never stopped eating, and never showed any signs of distress other than visual appearance. So, I just waited it out... eventually it cleared. Mind you, this was a 4 year old PBT in my care. I doubt a new addition would have done as well.
