Description
Emerald Crab (Mithraculus sculptus / Emerald Mithrax Crab)
A highly useful and popular marine clean-up invertebrate, the Emerald Crab is best known for its bright green coloration and its ability to control nuisance algae, particularly bubble algae. It is both functional and interesting to observe in reef aquariums.
Compatibility:
Generally peaceful, but can become semi-aggressive as it grows, especially if underfed. Best kept with fish such as clownfish, gobies, tangs, and wrasses. Avoid very small or slow invertebrates that could be targeted opportunistically.
Reef Compatibility:
Reef-safe with caution. Excellent algae grazer, but may occasionally nip at soft corals or steal food from sessile invertebrates if not adequately fed.
Diet:
Omnivore – primarily feeds on algae (especially bubble algae), detritus, and leftover food. Will also accept algae sheets, sinking pellets, and small meaty foods such as mysis shrimp. Feed 1–2 times daily if algae is limited.
Water Parameters:
- Temperature: 24–27°C
- Salinity: 1.023–1.026 SG
- pH: 8.1–8.4
- Minimum Tank Size: 60L
Care Level:
Easy – hardy and adaptable. Requires stable water conditions and occasional supplemental feeding in clean or low-algae systems.
Top Tip:
Feed regularly if bubble algae is scarce to reduce the risk of it nipping corals or becoming opportunistic. Provide rockwork with crevices for shelter and natural grazing.
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