i have a few questions about these guys, maybe you can answer them for me. how specific are they about the salt content in the water? and how big of a tank do you need to have for them (assuming no fish)? are they something that could have a small tank (1 or 2 gal), sand hill against one side, brackish water on the other and be happy? or do they need something bigger? also, how many is it good to have together?
(i'll admit, i hadn't really thought about them til now, but they are cute. i don't see a profile for them here, and haven't looked anywhere else, but you sound like you know about them.)