Please do not buy a cleaner wrasse.
Here is an excerpt from a well know aquarist.
The genus of obligate Cleaner Wrasses most celebrated for establishing stations in the wild that are frequented by "local" reef fishes and pelagics for removing parasites and necrotic tissue. Perhaps shocking to most aquarists, all the Labroides rate a dismal (3) in survivability, even the ubiquitously offered common or Blue Cleaner Wrasse, Labroides dimidiatus. None of the Labroides should be removed, not only for the fact that almost all perish within a few weeks of wild capture, but for the valuable role they play as cleaners.