Emerald Crab

Identity

Common Name: Emerald Crab

Scientific Name: Mithraculus sculptus

Other Names: Green Clinging Crab; Emerald Mithrax Crab

Family: Mithracidae

Type: Crab (decapod crustacean)

Native Range: Western Atlantic, including Florida, the Gulf of Mexico, the Antilles and Brazil.

Lifespan: Species-specific captive lifespan data were not established by this review; no numerical lifespan is asserted.

Overview

General Description: In Figueiredo et al. (2008), medium and large tested Mithraculus sculptus consumed more Ventricaria ventricosa than smaller crabs; alternative foods affected feeding. This does not guarantee eradication or justify withholding food.

Husbandry Basis: Hydro Habitats starting recommendations, not universal requirements. Adjust to footprint, food acceptance, condition and availability; avoid crowding and remove excess food.

Natural Habitat

Native Distribution: Western Atlantic, including Florida, the Gulf of Mexico, the Antilles and Brazil.

Natural Habitat: Reef and seagrass habitats

Substrate: Reef and seagrass habitats

Aquarium Setup

Minimum Tank Size: Hydro Habitats starting recommendation: 20 US gal (76 L); not a universal requirement.

Rockwork: Secure rockwork and loose frags; provide refuges and access to food.

Lighting: Provide lighting appropriate to the whole system; no species-specific irradiance target is asserted.

Water Flow: Adjust flow so the animal can maintain attachment or shelter and access food; avoid direct jets.

Space Requirements: Hydro Habitats starting recommendations, not universal requirements. Adjust to footprint, food acceptance, condition and availability; avoid crowding and remove excess food.

Special Setup Requirements: Match transfer water and avoid abrupt changes; protect intakes and reserve coral clearance.

Water Parameters

Temperature: Starting target: 74-80 F (23-27 C)

Salinity: Starting target: 1.023-1.026 specific gravity; use a calibrated seawater instrument and its stated reference temperature.

pH: Starting target: 8.1-8.4; not a species tolerance limit.

Alkalinity: Starting target: 7-11 dKH; not a species tolerance limit.

Calcium: Starting target: 380-450 ppm using the test manufacturer's convention; not a species tolerance limit.

Magnesium: Starting target: 1250-1350 ppm using the test manufacturer's convention; not a species tolerance limit.

Other Relevant Parameters: Ammonia and nitrite: not detected with seawater-compatible tests. Record each test's method, reporting basis (total ammonia as N or NH3, free NH3; nitrite as NO2 or N), units and detection limit; do not compare unlike readings. Interpretation of the free-ammonia fraction depends on pH, temperature and salinity. Monitor nitrate/phosphate trends and manage feeding/export for the actual system.

Stability Requirements: Use a biologically established aquarium with a documented history of stable conditions. Tank age alone does not establish readiness.

Husbandry Basis: Hydro Habitats starting targets, not species tolerance limits; use the test manufacturer's reporting convention.

Behavior

General Behavior: Observe the individual's attachment or shelter use, food acceptance and interactions; do not assume a trade label predicts behavior.

Compatibility

Compatibility Precautions: Compatibility is not guaranteed. Verify species and pairing, monitor feeding/contact, protect vulnerable livestock, and separate animals if injury occurs.

Contact Precautions: Coral and small-livestock damage is reported in aquarium care accounts; monitor the individual.

Diet & Feeding

Natural Diet: Algal and alternative-food consumption is documented in aquarium experiments; a complete wild diet is not asserted.

Captive Diet: Hydro Habitats starting recommendation: Algae-based and small meaty foods near shelter.

Feeding Frequency: Hydro Habitats starting schedule: small supplemental meals 2-3 times per week; not a universal requirement or nutritional-sufficiency guarantee.

Feeding Method: Hydro Habitats starting recommendations, not universal requirements. Adjust to footprint, food acceptance, condition and availability; avoid crowding and remove excess food.

Sexing & Breeding

Reproductive Strategy: Laboratory-reared Mithraculus sculptus passed through two zoeal stages and a megalopa before the first crab instar. This guide provides no breeding protocol.

Health & Special Sensitivities

Common Health Problems: Persistent loss of attachment, feeding response or coordination, visible injury or tissue deterioration warrants checking measured water conditions and obtaining appropriate aquatic-health advice. Appearance alone does not diagnose the cause.

Molting/Shell Problems: Crabs and shrimps have chitinous exoskeletons; snail shells are secreted by the mantle. Do not pull attached shell or tissue.

Copper Sensitivity: Do not use copper medication in a display containing these invertebrates. Treat fish separately under appropriate aquatic-health guidance; a reef-safe label alone does not establish safety for the animal or system.

Beginner Suitability

Beginner Friendly: Conditional; assess readiness and care demands.

Why: Assess readiness from stable conditions, habitat, feeding and monitoring capability; no hardiness or beginner-success guarantee is made.

Before You Buy

Important Considerations: In Figueiredo et al. (2008), medium and large tested Mithraculus sculptus consumed more Ventricaria ventricosa than smaller crabs; alternative foods affected feeding. This does not guarantee eradication or justify withholding food.

Compatibility: Compatibility is not guaranteed. Verify species and pairing, monitor feeding/contact, protect vulnerable livestock, and separate animals if injury occurs.

Diet: Hydro Habitats starting recommendation: Algae-based and small meaty foods near shelter.

Adult Size: No verified aquarium adult-size range is asserted here; confirm expected size for the identified animal before stocking.

Long-Term Care: Assess readiness from stable conditions, habitat, feeding and monitoring capability; no hardiness or beginner-success guarantee is made.

Species-Specific Information

Anything important that does not fit above: In Figueiredo et al. (2008), medium and large tested Mithraculus sculptus consumed more Ventricaria ventricosa than smaller crabs; alternative foods affected feeding. This does not guarantee eradication or justify withholding food.