Green Emerald Crab - Mithrax sculptus. Picture taken January 2001.
Nikon Coolpix 950 digital camera, tiffen +7 close-up lens, full flash

Green emerald crabs make questionable additions to reef tanks as they may or may not be reef safe. The larger the tank the safer they tend to be do to increased grazing area. The crabs typically do not grow larger than 3 inches in size.

They tend to be primarily algae eaters but have been known to capture small fish and pick at coral polyps.

Green Emerald Crab - Mithrax sculptus. Picture taken January 2001.
Nikon Coolpix 950 digital camera, tiffen +7 close-up lens, full flash

These little buggers have a pretty ugly butt. You have to be pretty careful when purchasing Emerald Crabs since many different crab species are sold as Mithrax sculptus.