There is not much you can do about ich. The best thing you can do is prevention. New fish get stressed by shipping and changing water chemistires repeatedly.

I just recently bought a blue hippo tang and it had ich on it, my cleaner wrasse cleaned the ich granules off of it and I fed the fish garlic soaked mysis and now the fish is fine. If you have good water quality, good food, and stable water temperature that is the best defense against the ich.

Even with all that you can still lose fish to ich especially if the fish was too far gone by the time you got it.