Agreed with shred,In order to quarentine the right way you have to start with your very fish you get and quarentine every one added,Now ich is in your tank and will always be there.Its no big deal healthy fish will fight it off.Imo every one of us has ich in our tanks, its just like a cold to fish,just keep it fed well and try and keep your hands out of the tank so the fish doesnt get stressed.Some people will say take the fish out and put in a hospital tank and treat with copper meds but all that does is stress the fish out more and soon as you put it back into your display it will get ich again.So just keep the fish fed well with garlic foods and it should do fine as long as its not stressed.Once a fish realizes the aquarium is his new home he should never get ich again.