i bought this little guy to at the lfs....several times sad to say......i got a hunch on these. i beleive these crabs are just plain sold wrong. if you look at there eye stalks they are long with the eye being at the top, the only crabs that i know that have that unique setup are fiddler crabs and land crabs. mine died withing several days on all three counts. i think these crabs are just brought in to the pet store cuz there "pretty" and sadly no one knows how to properly care for these creatures, i get the impression that this is a crab that comes out when low tide hits and they feed on the micro fauna/flora in the sand/mud and unless you have an area where they can rise above the water they will die
just my 2 cents
~Gill~