I have one in my Reef, and they are Very neat fish. mine was about 2 1/2" long when i got him, and eating right out of my hands. Definatly a great fish for the reef. the Sargassum & Blue throats are known to be reef safe. Havin a sargassum, i can vouch that they are safe. all my cleaner shrimp are still alive.
as long as your tanks parameters are good, and the fish is eating at the LFS, pick him as soon as you can