I just started my 32 g biocube, and i am about to add fish. I'm wanting to get some fish and inverts that will add character, so I am thinking either a pistol/goby pair or a yellow headed jawfish for burrowing. I've read jawfish need 5-7" of sand. My sand bed is about 2" because I planned for pistol/goby. But recently I've read that the jawfish only need 5-7" in a mound for their hole and not everywhere else. Is this true or does the hole tank need to be deep?