Emerald Crab (Mythrax Sculptus)

The Emerald Crab is a popular and effective addition to marine aquariums, specifically known for its ability to control nuisance algae, particularly bubble algae (Valonia spp.). Its vibrant green coloration and active scavenging behavior make it a useful and visually interesting member of the tank's cleanup crew. However, while generally reef-safe, there is a small risk that some individuals may nip at corals, particularly if they are underfed or there is insufficient algae in the tank.

Care Information

• Maximum Size: Up to 2 inches.
• Tank Size: 20 gallons minimum, with plenty of rockwork for grazing and hiding.
• Diet: Omnivorous; primarily feeds on algae, especially bubble algae, and detritus. Supplementing with sinking pellets, seaweed, or meaty foods can help prevent it from targeting corals.
• Water Temp: 74-80°F.
• Salinity: 1.020-1.025.
• Aggression: Peaceful; typically coexists well with other invertebrates and fish. However, it may show aggression toward other crabs in smaller tanks.
• Skill Level: Beginner; hardy and easy to care for, making it a great addition to both beginner and advanced aquarist setups.
• Reef Compatibility: With caution; while generally reef-safe, there is a chance that some individuals may consume corals, especially if they are not receiving enough food. Monitoring behavior and ensuring they are well-fed is crucial to maintaining their reef compatibility.

Special Feature - Bubble Algae Control
The Emerald Crab is particularly valued for its ability to consume bubble algae, a common nuisance in marine tanks. While it is not guaranteed to eliminate the problem entirely, it is an effective natural solution for keeping bubble algae under control. However, providing supplemental algae or other food sources is important to prevent the crab from turning to corals or other tank inhabitants as a food source.

Compatibility
While Emerald Crabs are generally peaceful, it's important to monitor their behavior in reef tanks to ensure they are not nipping at corals. Keeping them well-fed with algae and detritus reduces the chance of this behavior.

Coloration

• Caribbean Region: The Emerald Crab is typically bright green with a smooth, rounded carapace and long, powerful claws. Its striking green coloration and active scavenging behavior make it a standout in any reef or marine tank​.

Typical Habitat

• Distribution: The Emerald Crab is native to the Caribbean and Western Atlantic regions, where it inhabits coral reefs and rocky environments. It prefers areas with plenty of rockwork for hiding and grazing on algae.