You could quarantine the fish and try meds. If you can't get him out of the display, assuming that's where he is, there are varying opinions on the effectiveness, but you might try mixing garlic (either the extract you get at the fish store, or finely minced) in with the food. I don't know that it will "cure" ick, but may help your guy fight it off.
I have a small blue that's been fighting it off as well. I think the garlic may be helping. A cleaner shrimp in the tank may help as well. (or so I've heard) I'm no expert and you'll probably get better replies than mine, but these are a couple things you may want to consider.