[OCDP]

I would watch closely. If they've had ick for that long.. surely they are not happy fish. They may look fine but they wont be happy..

I haven't had ick on tangs, just clownfish. I am perhaps lucky... but my clown got it fairly bad. What I did.... leave them alone! Zero stress. Do waterchanges in a manner that will not scare or spook your fish (it's not hard) Keep tank paramaters pristine. *Feeding with Garlic** This saved my fish ( I think ) I fed every day for two weeks, no ick. Ick has been gone ever since and has not made a comeback.

I think if your fish is stress free, living in great water quality.. and is being fed daily keeping his belly stuffed and immune system up... they can and will fight it off. But a lot of it depends on you.

Just my experience so far.