There was a thread about this a few months back that might be worth looking up. I commented on that thread and I'm going to repeat myself here although some people on the original thread disagreed with my assessment:
I have two ocellaris clowns. Several months ago, I brought home a royal gramma that had ich. Small black spots started appearing all over my clowns -- fins, scales, etc. The clowns did not get any white ich spots while the gramma was covered in them. At this point, I had no anemones and my corals consisted of a montipora, gorgonian and toadstool.
I put all of my fish through TTM. My gramma died. My clowns survived, and the black spots disappeared in the middle of TTM.
My clowns now live among two RBTAs, a frogspawn, an octospawn, zoas, a nepthea, galaxea, GSP and my old corals. No black spots whatsoever, and they regularly swim into the anemones and some of the corals.
That's my experience. Good luck to you.