If you do a search you will find a whole "primer" series on the Copperband Butterfly. Lots of good reading in there.
That said, I've had one over a year. I QT'd it with another fish until it learned how to eat. Once in the reef it decimated all my feather dusters and aiptasia. I feed live black worms heavily, and also give it fresh clam, mysis shrimp, and just recently it started eating nori from the clip that I provide for my tangs.
It's an awesome fish but success stories are hard to come by. Look up that thread, you won't be sorry.
I do have a fairly large tank, 180 gallons and the CBB does use all of it. Right now it's about 4 inches.