I love lions but never had the time or money to set up a tank for a couple. My local chinese resturant has a 450 gallon or so tank with 4 lion fish in there and your right about them not being active. They just sit on top of the rocks the whole time i am there. They are MASSIVE though. I would say that are 12" and the spines are about the sive of a dinner plate off the body. I am thinking on a 155 gallon with 3 in there. What do think?