I have two ADF's in a 5gal tank...I dont have sand as yet but have rounded gravel. I have a lump of bog wood for them to hide under and also live plants and soft edged fossils. They have to share with a male molly and two male guppies at the moment, but always have enough food..I watch them a meals times as they are so funny!
Mine have defrosted bloodworms, I find they like the red ones best. They do like tubifix worms too. Mine two will also eat the tablet food that you can stick on the side of the tank, not too sure if its any good for them though!
I have also taped up around the holes the cables go through as they can be known to be excape artists.
Fiona