Pretty cool little dudes, I've only seen them a couple of times - I believe they need access to the surface occasionally so you might need to add a little platform or a piece of bogwood that protrudes out of the water, apart from that they are pretty hardy apparently, they fly out of my LFS anytime there in stock along with the Red Thai Crab. Though buyers come back after a while wanting to know why they died, even though they where told about the need for surface oxygen.