KurtG wrote:

My tang has been itching itself for weeks/months, and often allows the
4-stripe damsels to "chew" on him. However, he's a nut case anyway, so
I didn't worry about it (maybe a newbie error). Now my Coral Beauty has
some bright white dots on it, and it's starting to itch as well.

Could this be marine itch?

Sounds like ich (oodinimum). Has the tang been going through a cycle of this?
That is, does the tang exhibit symptoms for about a week and then have no
symptoms for about a week? And when the tang has no symptoms, do there seem to
be a bunch of very tiny white dots doing loops in the water?

If so, that's what you have.

Take *all* the fish out and transfer them to a hospital tank. Treat them there
with copper (I prefer "CopperSafe") and keep them there for 4 weeks to allow the
parasites in the main tank to die.

George Patterson
Forgive your enemies. But always remember who they are.