So im doing a 20 Gal Reef with the "oddball" choice of fish being a Pearly Jawfish and considering they make their burrows using their mouths, what would be the ideal grain size for them? I remember when the Northern Seas Aquarium at the Point Defiance Zoo was open, they had a Pearly Jaw Colony that had considerably thick / big sized grains as their substrate and they seemed to do well, would something like 1-2mm be okay for them?