When can I add fish to my tank

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I have a 65gal FOWLR tank. I had an assortment of fish 4 damsels, a foxface and powder blue tang. After the the tang had been in the tank for about a month, it developed ich and died, all of the other fish succumbed to the ich too and paraished, except for the foxface who seems to have recovered. Now, I am a little confused on what I should do. I was told and read that once a tank had ich that it would need to be fishless for about eight weeks to kill of the parasites. I was goning to do this thinking the foxface would die, but since it has not and now appears to be healed I an not sure what to do next. I would like to re-populate the tanks but I want to make sure the ich is gone.