Emerald Crab - Mithraculus sculptus

Emerald Crabs are named for their coloration, which varies by individual, ranging from the eponymous deep emerald green to olive, or even a dull gray. They make excellent scavengers, and are widely sought after for being one of the few species that will consume bubble algae. They're a nocturnal species, so once added, they'll rarely be seen in your aquarium, but they make an excellent, if stealthy member of your clean up crew.                

Care

Emerald crabs grow to a maximum size of 2.5 inches, and should be provided with plenty of room to forage and hide during the day. Like other invertebrates, they're intolerant of copper and rapid changes in water chemistry. Care should be taken to slowly drip acclimate them.    

Diet

Unlike most clean up crew, it's advisable to ensure Emerald Crabs remain well fed, and to provide supplemental feedings if algae becomes sparse. As with most crabs, Emeralds are opportunistic, and will eat coral or even fish if they get hungry enough, though they are completely reef safe when properly cared for.