They will hide in the sand it may b a day or 2 b 4 u see it .but it will come out, after it do come out it will only be for a few hours then back into the sand they go.. As time goes by he will get use to the tank and spend more time out.
I have a Meleagris..when first placed in th DT it went right into the sand, but came out the next day and swam iradically all over the tank for a few days ignoring all foods....took three days to settle in and began eating...now it eats everything and like clockwork up at dawn and into the sand after the halides go out at night....it's not unusual for them to stay in the sand for a few days or longer when they don't feel secure or unconfortable....