Aloha,

Mark  

Ich (or its marine counterpart) is in every major body of water. I have seen others talk about developing ich in an isolated tank, when no new fish are added, and the only things put into the tank are: a)food, and b)water durring water changes. No plants/Corals added, as the you would think, nothing was added to the tank.

This leaves three possibilities:
First of all, it's possible that the ich continues in the tank. The Skeptical Aquarist says, "This cannot be! There is no dormant stage of the ich life cycle." The Skeptical Aquarist is right about the latter, but presuming that this precludes the idea that the ich has continued in the tank is a major mistake. Because of the method of reproduction, all it takes is one little parasite growing on a single fish (even in the gills) to keep the infestation going. In a healthy fish, one or two parasites aren't a problem. It's really only in stressed fish, or when the fish are completely overwhelmed, that the parasite can take over the tank. 
Second, it's possible that the parasite was added by the food. When we're talking about flake food or pellet food, however, that doesn't really work. We know that the cysts can't survive drying out.
Third, the parasite was introduced to the tank via water changes. The cyst is relatively protected against a wide variety of chemicals. I wouldn't doubt that chlorine / chloromines was one. Those chemicals kill 99.9% of bacteria and viruses. All it takes is one cyst to let hundreds of individual parasites into the tank.

In either the first or the third case, it can be presumed that, while ich isn't necessarily present in every one of our tanks, we also can't presume that the lack of an overt infestation means the tank is entirely free of the pest.

This thread, also listed in the Reefkeeping Tips, pretty much gives all my recommendations and instructions for GO treatment:

Aloha,

Mark  

Do you feed garlic on a regular basis or only when you see signs of trouble?  Do fish get Ich after being in the tank for a while?  I thought it was only a concern when introducing new fish.  

Aloha,

Mark  

Yes, I feed all over the tank to keep old fish from scaring away the new fish.

 

Solgar Garlic Oil Perles are something I never go without. I have a large supply and would be happy to share. Just call me at 808-345-1049. Midvale is next to Murray. GO has saved more of my fish than I know. In the early days of my hobby, I lost a good third of my new fish to Ich. Of course, those were the days before we knew about the benefits of UV and O3.

Aloha,

Mark  

I am going to go home tonight and  provide 2 feeding spots for Nori on each side of the tank to try and separate the tangs and Foxface as much as possible. The fox face ate some, Mysis last night as well as this morning so that's a good sign at least, and he did make it through the night without much trouble I assume, I kept an eye on things for a few hours after the lights went out. 

I just find it weird that the YT didn't display the same, behavior with the Tomini Tang when he was introduced. he just more or less followed him around the tank, but never touched him.

Aloha,

Mark