Ok, here is the story on my achillies.
I got him from live aquaria. I haven't seen an achillies in the lfs in SC in I don't know how many years, but its been at least 5. I'm sure they get snatched up but I am there regularly, the owners say they have gotten too expensive. Plus, I think they don't want to risk it with such an expensive fish.
I drip acclimated him upon arrival over the course of about 1.5 hours to the qt tank that was at 1.23. I think the water he came in was closer to 1.25. Wish I had asked this before I ordered, but hey. Now I know. He went in a 29 high qt tank with one koralia, two small pumps with tubes circulating water around and an airstone in a piece of foam. i put a little sand on the bottom and a few small pieces of live rock. I had an old floursecent light from this tank when I originally set it up as my first salt water in 1989. So, it was low light by todays standards.
He didn't eat much at all for a couple days, but to my surprise, and benefit, he preferred mysis to anything and wouldn't eat nori until it was softened up and shot thru a powerhead, This seems kinda normal based on everyone in here's experience. After about 1.5 weeks he started eating more aggressively. He showed no flashing or any signs of disease. I left him in here doing 2 gallon water changes with water from my dt almost daily to ensure no cycling issues or trouble from the fairly excessive left over flakes and pellets. Even some pieces of mysis. He is picky about size. He is a juvi that is about 3.5-4".
After 4+ weeks of qt I decided to move him to the dt. Did a 2 hour drip acclimation, though he was in water pretty close to the dt from the water change regiment. I turned the lights off, and put him in. A mild melee ensued between him and my purple, or should I say my purple against him. This lasted about 12 hours. After that a basic confirmation of the new pecking ordered ensued. Oh, I forgot, I added some live rock and rea-arranged one of the islands in the tank to help with aggression as well as this was necessary to catch a coris wrasse who had served his purpose catching and eating the bristtleworms in the tank. After the aggression bothered me a bit I put an egg crate seperator in the the middle of the tank at bedtime(for me) to split him and the purple up. When I came in the next morning, it was up but there was a slight crack in one side and he was on the other side with the purple and yellow tangs so I took it back out and they have since gotten along.
After about the 3rd day, ich showed up in the form of two small spots on him. Did I miss this in QT? possibly, never treated with copper because never saw symptoms but having seen and read this thread now I would have and will with all fish in the future. more on that later. Its possible he picked it up in the tank I suppose. No fish have had it and have had no issues or added anything for some time, maybe four or five months at least. There is some rock in there from a tank where a fish had ich years ago. Also, I haven't been qt'ing corals though that will change with the next purchase.
So, he has had ich for about a month on and off. He is pretty fat and eating well and "fighting it off" whatever that means. Seems to mean to me they die most of the time based on this thread. So, I have about 15 fish, mostly anthias and four other tangs, a fairy wrasse, and few cardinals. Today i got the ball rolling on three 50 high acrylic tanks to upgrade my sump for my coming new build. Once I get those, I am converting the current sump, an old 55 long to a qt as well and qt'ing the whole pack as well as letting the tank go fallow for 3 months. I think I might just take the cardinals to the local fish store, all they do is hide in the rocks and display conspecific aggression. That leaves only about 10 fish and I think they will make it 3-4 months in a stable qt environment. Mr. Purple may or may not go back, He is a beauty but he may not do well in qt and he is not going in with the achillies in qt. They are fine now in the display but there is lots of room and everyone has a hiding spot/cave.
So, thats where I am. Oh, did I mention I love the achillies, by far my favorite in the tank and the most personable.
I am going to qt everything I get for at least 4 months from here on out, Its not worth getting my tank where i want it and going thru this. No other fish are sick yet, but you never know when. I don't think the achillies will ultimately beat the ich, its getting worse each cycle, not better....