You can't cure the display... Any methods that are effective against ich (hyposalinity and copper) will kill the inverts in your tank. You have to remove and quarantine all the fish in your tank. You can't treat just one, because they have all been exposed.
Most people prefer hyposalinity treatment over copper treatment. It seems to be less stressful on the fish. But either way you go, your fish will have to remain in quarantine for about 2 months, and you have to keep your tank fish-less for 2 months.
Is the foxface still eating? Is he being active and swimming? If he is, then another option is to just let him ride it out and recover on his own. Most fish are able to overcome an ich outbreak on their own if they are eating and you have good water quality. But you will still always have ich in your tank, even if you never see it on any fish.
