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If you've cycled your tank and your parameters are all well and good I'd say leave the fish alone. See how well he eats tomorrow and let us know. New fish can tend to hide out a bit until they're comfortable with their surroundings.
Not knowing where you are, I can't be sure of the time zone, but your post was after midnight here. If it is dark, the six line wrasse will hide under a rock, or even bury itself in the sand and surround itself with a clear mucous cocoon. It sleeps inside of this to mask its scent from predators.
So as long as it moves during the day, this is perfectly normal and healthy.