Ich...

My advice..get a QT and move the fish over to it if possible.

a few of us have dealt with this issue.

depending on the source you get..FW dips may or may not have much effect on the ich as the trophonts are usually burried deep in the tissue and are un affected by the FW.

you can try feeding garlic to help bump the immune system.

I am currently housing several fish for 4-6 weeks in qt before adding to a tank that i am trying to rid of ich.

I am running a uv sterilizer, feeding garlic to the lone inhabitant and using reef safe meds(hich by them selves are usually not very effective)
going on 1 month so far so good(knock on wood)

ick is an animal which goes through a life cycle (cyst, larvae, adult, give or take?). the form we all hate is the adult stage that feeds on our fish.

now, in my opinion, if you refuse to have a QT tank or hospital tank, your waiting for disaster. if one fish in a system shows ick, the rest have it also but perhaps in much less noticeable infections. i think i have read that ick goes after the gills and by the time you see it on the body, the gills are heavily infested.
i tend to use copper as my first choice of treatment. copper can be a nasty thing and can do as much damage as it does good. but it works wonders and is my main choice. i would recommend removing ALL fish from the system and treating them in a seperate tank. keep the main system fishless for 50-60 days so that the ick dies out by starvation. ick cannot survive on inverts or corals. after the 50-60 days, you can add the fish back and if done right, you will never see ick again unless you re-introduce it.

i have successfully defeated ick in my reef with this method and i highly suggest a hospital tank for all fish keepers. i also recommend you treat all new fish for ick/internal parasites so that you keep the system free of problems. i use praziquantel for internal parasites, i use the jungle brand.

uv sterilizers are designed to kill algae spores, and it takes a higher wattage to kill the freeswimming stage of ick. through extensive reading on reefcentral, it seems most uv sterilizers do nothing against ick.
also, reef safe meds in my opinion are useless against ick. i have never seen a reef safe ick medication claim to cure ick, but to just help control it. pay attention to the labels and analyze what the product REALLY does. my way of thinking is if its safe for a reef, its safe for the ick. also i like to say that if it causes cancer in California, then it must work! (some aquarium meds have this warning on them, and they work!)