A 125 gallon or larger aquarium with plenty of live rock for hiding places and moderately aggressive, active fish such as Angels, Tangs, and smaller Triggers is an acceptable environment. Keep only one specimen per tank. Although they will not bother corals, they will eat any small crustacean such as snails or crabs.
The Harlequin Tusk Wrasse diet should include vitamin enriched frozen mysis shrimp, vitamin enriched frozen brine shrimp, and other meaty foods along with a high quality marine flake and marine pellet food.
Source: Live Aquaria - Photo used as indicative only.