I have an empty 20gal and noticed a nice pair of steatocranus casuarius (sp?) at the lfs. I know absolutely nothing about them other than they look really cool, seem healthy, and eat like pigs. So, is a 20 long ok? Will they need bigger diggs? What should I know about them other than water parameters? They would have the tank to themselves... Any help would be great before I decide to buy.