If you find them picking at the sand you can also try target feeding them. I target my vampire shrimp just to make sure they get enough to eat.
55 gallon elephant nose tank.
16 gallon vampire shrimp and snails
70 gallon elephant nose tank, Gonzo the elephant nose and friends!
30gallon borara merah and brigittae green, red longfin bristlenose, shrimp, ninja, taiwan,bamboo, and snails.