Most of them will adapt and eat very small particles of almost any prepared food. One VERY important thing with this species is to have a rock with holes in it for them to sleep. Many of them will die from stress if they dont' have a 'safehouse' to sleep in. As soon as the lights go out they will shoot head first into a hole, and spend the night.
If you are not sure if there is enough parasitic food for them, they will take very small (and I mean really, really small, like pinhead size) pieces of clam, squid, and shrimp. We have had one for over 18 months, and he's doing great. The common cleaner wrasse (the most common one found in LFS) will change color at about a year of age, they become a milky white with a black stripe, and lose their blue. Still beautiful!