going by your signature you have plenty room in your tank if you wanted to get some, dont expect to see them a great deal mind you, when we sold them in the fish shop I worked in we never knew if we had any or not because they were always buried, having said that I do like them myself and the pleasure is in the waiting.
Someone else might be able to adv you on what kind of substrait is best eg sand or fine gravel etc because they do like to bury themselves (assuming you plan to get some that is, unless your question was just a general one)