I kept an Achilles Tang for over 5 years. We bought our first house in S. Carolina and the guy didn't want to move the 125 gallon tank, so we took the tank with the house the Achilles had already been in there for 2 years, so he lasted more than 7 years in the tank.
I find these fish very hardy once established, he survived many beginner errors on my part. In general I think an open tank with lots of swimming space is important, at least 6 feet long worth of tank, I would say my 125 was a bit small for him. Plenty of good water flow, and excellent, consistent water. If the ph dips under 8 at any time this fish will let you know with mopey behavior immediately. Perhaps most important is providing these fish with a good diet and plenty of greens, every morning I would put a full sheet of seaweed in for him to enjoy.
One thing to remember in spite of their fragile reputation, this can be a very aggressive Tang. In a tank with 2 Triggers, a Lunare Wrasse, and a few other aggressors, the Achilles was the undisputed king of the tank. They do not tolerate their own kind very well, mine killed a Yellow Tang very quickly I tried to add. He would abuse any new arrival for about a day or so just to let them know who the boss was.
I have owned a lot of great and interesting fish, but the Achilles is still my all-time favorite I have kept.
Unfortunately this is the only pic I have of him....It was before we had a decent camara
