It sounds like you are dealing with a creature that is not very common. I am very suprised that no one has had anything to add about your fish. I found this description of a close relative of your fish. Maybe it will help you.
A 70 gallon or larger aquarium with generous amounts of live rock, hiding places, and swimming room provides a good environment. It will do well with others of its own species as long as there are adequate hiding locations and plenty of space. It will eat invertebrates such as worms (includes fireworms), crustaceans, and serpent stars. It is a nocturnal fish and hides while the lights are on.
When first introduced into the aquarium, live saltwater feeder shrimp
should be used to entice this fish to eat. The diet should vary between live feeder shrimps, freeze-dried shrimps, chopped marine meats.