cool, well-oxygenated water is key. Lots of current. I have kept them on river sand collected locally, but I think small, non-abrasive gravel should work fine. I defintely recommend a powerhead or two, as they seem to thrive in pretty strong currents. No idea in keeping them in groups. I've only kept some collected juvies (under 6") for brief periods but I'm also considering getting a trio from carolina biogical when they become available. They are real monsters, and ugly as hell to boot.