Not a very good analogy, I know, but I consider a tank with fish that have ICH similar to a kennel with dogs infested with fleas. Both creatures itch and are constantly being bitten eventhough to our eyes they look okay since they eat and move around okay. The ICH/fleas are there, you just have to look closely (microscope for the fish).
When I chose to remove my fish and treat them for ICH, they all were eating great and only a few showed signs of ICH but I knew the other fish had it also. I could not bare to look at the reef any longer
....So I treated them! They look fabulous and are ICH free!!
The only way to rid your tank of ICH is to remove all fish to a QT, treat them, and leave the main display fallow for at least 8 weeks. I am currently doing just that and am going on the 7th week in QT. It can be done successfully and IMO is the most responsible thing to do.
Check out all the sticky threads in the Fish Disease & Treatment section:
http://www.reefsanctuary.com/forums/...es-treatments/
Tons of info there to explain how to treat and prevent ICH
