New Blue Tang has Ich, how to Treat?

[Carmen]

QT tank may really be more stressful for the fish than it's worth. Unless you plan to go fallow for 6-8 weeks in the display , then QT each and every addition to the display in the future then the QT is not helpful. Once you add him to the display the ich is already there...he will get it again.

My regal tang is very sensitive to ich spots as most are. Each time the tank is disturbed whether it be moving things around or a new addition she gets a few spots. But...she is a pig and eats anything. She just fights it off.

Your fish will have a much harder time recovering while under stress. A 10G QT is tough to keep stable and healthy. Not that the QT method is not effective but it must be used EVERY time, cinsistently, and for the full QT time (and now fallow time).
I personally find a healthy fish will fight the ich better in a healthy display tank. And yes, I did try a QT tank... Unsuccessfully. I have had a few losses of new fish but MOST have done very well. You do stand the risk of infecting the rest of the tank but for me, that is a risk I have chosen to take.
I hope your fish recovers well! I have become very attached to my Regal tang and know the feeling of wanting to do everything you can to keep them happy and healthy! Good Luck.