Emerald Crab

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Hug a mod Nano Reef Moderator
Retired Moderator ⚒️
Dec 27, 2004
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Long Island, NY
Common name(s): Emerald crab, mithrax crab, Emerald Mythrax crab

Scientific name: Mithrax sculptus

Family: Majidae

Origin: Carribbean

Maximum size: Up to 2 1/2"

Reef compatible: Yes

Care: Emerald crabs make up a member of what we call 'the cleanup crew'. They scavenge the aquarium for leftover food or algae and help to keep a marine aquarium clean. One of their claims to fame is that they will eat bubble algae (valonia) which is a nuisance hitchhiker on live rock. The emerald crab is green in color and has hairy rear legs. As it grows, it will molt and leave it's chitinous layer behind looking as if it had died.

Feeding: This mithrax crab, as mentioned above, will pick the LR clean. If food becomes scarce, emerald crabs can pick on fish or corals when they get larger. They will eat virtually anything including flake, pellet, frozen foods and seaweed.

Sexing: Difficult

Breeding: There are reports of Emerald crabs releasing larvae. Mithrax crabs will hold the eggs inside of the flap on their bottom side until they hatch, afterwards releasing them in a planktonic state. Offspring are so sensitive that they rarely survive.


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