Description
Mithraculus sculptus (Emerald Crab) is a popular, hardy, nocturnal reef-safe scavenger (up to 2 inches) known for eating nuisance bubble and hair algae. Native to the Caribbean, they feature a vibrant green, flat shell and hairy legs. They require plenty of live rock for hiding and are generally peaceful, though they may prey on small fish or corals if underfed.
Key Details for the Hobbyist:
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Care Level: Easy.
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Diet: Omnivore/Herbivore. Consumes bubble algae, green hair algae, and leftover meaty foods.
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Tank Conditions: 75–82°F (24–28°C), pH 8.1–8.2, salinity 1.024–1.026.
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Behavior: Generally peaceful, but can be opportunistic; may harm small, slow fish or sessile invertebrates if not enough algae is available.
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Size: Up to 2 inches (5 cm) in width.
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Habitat: Requires plenty of rockwork/crevices.
Reef Safe Status
While generally considered reef-safe, Mithraculus sculptus is best described as "reef-safe with caution," as they may pick at soft corals or LPS if they are underfed. They are considered highly effective for managing bubble algae (Valonia) outbreaks.
