The Threespot wrasse inhabits sandy areas of reef flats, lagoons and semi-protected seaward reefs.
Juveniles wrasses are found in shallow and protected coastal waters; adults fishes live in a depthrange to about 30 meters.
Halichoeres trimaculatus feed on sand and rubble dwelling invertebrates (crustaceans, mollusks, forams, polychaetes, fish eggs, and small fishes).
They have the habit of following sand-disturbing fishes such as goatfishes in order to intercept escaping prey.
This wrasse lives reef associated and is found from 1-30 meters.
Juveniles occur in shallow, protected coastal waters.
This species is occasionally collected in the South China Sea for the aquarium trade and for the live fish trade, and is sold in China.