I have one for about 5 years in a reef tank. I took it out last year because it developed taste for my coral polyps. Before that, it was eating only flake which I tried hard to get it start.
I got it as a small juvy, about 2". It started feeding when I use the mussel, cut off the meat and let it pick the remain on the shell. Then I use nori then flake.
It is healthy and still loves flake but I want to hold it a bit longer before send it back to the main tank.
The trick is to obtain a healthy speicmen and lots of patience.