I've heard they are delicate to but my own personal experience is they are pretty tough. I base this on my own experience of having a LFS sell me one (really gave me the hard sell since I didin't want him at first cause I thought he was too large for my tank) when I was first starting out and didn't know any better. I put it in a 37g tank and it survived over a year and a half while I learned about keeping a salt water tank. This guy had to be tough as nails because I made many many mistakes and he never had a problem. I ended up trading him to a LFS because I read they were not reef safe and I was turning both my tanks into reefs.
Now I wish I had kept him because this was easily the most personable fish I have ever owned. always swiming out in the open, never aggressive toward other fish, would eat out of my hand from day 1 til the day I traded him in.