They choose to live at either. Its not like the lta's that most always stay on the sand.Mine was in the sand as we'll. I would feed it small pencil eraser size pieces of silversides,fresh clam meat,fresh shrimp. Find what it likes and go with it. I feed mine that size pieces everyday untill the colour came back and then started about twice a week. Most like silversides but you never know.
Here is a link to liveaquaria with abit of info:
http://www.liveaquaria.com/product/p...cfm?pCatId=633