Steve, I guess I didn't make myself very clear last night, most likely due to lack of sleep!!
sometimes the fish have to come out.. but he said in an earlier post that his tang seemed to be getting better, That was the reason that I said to leave him alone......sometimes it's best (in my opinion) to let them work it out. You have to decide the level of care that is required for each individual fish.
In my experience, I have too much live rock and corals to try and catch a tang, without tearing down the whole tank, I have done that! and I will do it again if it is required..
My Sailfin tang has had ich twice, the first time he was really young, but with garlic and vitamins, and of course letting him eat all he wanted, he fought it off, if it was bothering him I would take him out and treat, but he is in excellent health.
I have done alot of research on this and as all you guys know there is a wide range of treatments you can use. Copper is dangerous.. The reefsafe meds are a waste of money (just my experience,) A freshwater dip and a hyposalinity treatment seems to be the best I have used.
Peace.