Ginger was suggested and discussed years ago, although no proof it does anything. I've treated ich in the past this way. Food soaked in selcon and crushed ginger. Agree with others to increase feeding.
Copper only solution really, but I also am in the camp of letting the fish fight it off, and that if you try to capture and treat, the stress associated with that process may be more harmful than not. With that said, I've not lost a fish to ich in over 10 years.