I have a 150g tank that has a flame angel, blue tang, 2 clown fish, 2 damsels and a flasher wrasse and every once in a while the blue tang will get a spot or two...i leave them alone because i have never had good luck with treating ich. The fish in my tank are fat and healthy and after a few days or even the next day the spots are gone. It may not be ich but according to my lfs
it is present in your tank all the time. Anyway, I used to get all twisted about it but now i just let it go. All my fish in my tank are going on 1 yr. Maybe it's not ich at all, but keeping my fingers crossed. Lately for me that seems like the best technique for success.