Description
Antler Crab (Manucomplanus varians)
(Also known as Decorator Crab, Coral Crab, or Spiny Antler Crab)
Overview
The Antler Crab (Manucomplanus varians) is a fascinating and unusual marine crab species best known for its elongated, antler-like legs and habit of camouflaging itself with bits of coral, algae, and sponge. With its spindly frame, textured carapace, and natural disguise, this crab blends seamlessly into live rock environments, making it a unique and functional addition to specialised reef or display tanks. While peaceful and nocturnal by nature, it should be housed with care, as it may opportunistically feed on soft corals or polyps when hungry.
Origin
Native to the Indo-Pacific region, including the Coral Sea, Great Barrier Reef, Indonesia, and Fiji. Commonly found in reef crevices, coral rubble zones, and rocky shallows, where it hides during the day and forages at night.
Feeding
The Antler Crab is an omnivorous scavenger that feeds on organic debris, small invertebrates, and algae. In captivity, it adapts well to a varied diet. Feed 3–4 times per week with:
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Mysis shrimp or finely chopped seafood
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Sinking marine pellets or algae wafers
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Dried seaweed (nori)
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Occasional meaty foods like clam or krill
Supplemental feeding ensures it doesn’t resort to nipping at sessile invertebrates or corals.
Lighting
Low to moderate lighting. Manucomplanus varians is nocturnal and prefers subdued light levels with shaded areas for daytime shelter.
Water Flow
Moderate flow. Provide consistent water circulation to mimic reef environments while maintaining calm zones within rockwork for the crab to rest during the day.
Placement & Habitat Setup
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Provide plenty of live rock and coral rubble for hiding, perching, and camouflage.
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The crab often decorates its body with small algae or sponge fragments for concealment — ensure natural materials are available.
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Use fine to medium-grain substrate to allow movement and foraging.
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Avoid bare tanks, as the crab relies on cover for security.
Tank Mates
Reef safe with caution. Compatible with:
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Peaceful reef fish (gobies, blennies, tangs, clownfish, etc.)
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Other non-aggressive crabs and shrimp
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Snails and starfish (with observation)
Caution with:
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Polyps, soft corals, and zoanthids — may nip when hungry
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Slow-moving or small crustaceans
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Predatory fish (triggers, puffers, large wrasses) that may prey on crabs
Aggression
Generally peaceful but opportunistic. The Antler Crab rarely initiates aggression but may scavenge on vulnerable tank mates or stationary invertebrates. Maintain good feeding routines and observe interactions.
Experience Level
Intermediate. While hardy and adaptable, Manucomplanus varians requires a mature tank with stable water conditions and ample rockwork. Its unique behaviour and diet make it best suited to aquarists with some marine experience.
Water Parameters
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Temperature: 24–27°C (75–81°F)
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pH: 8.1–8.4
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Salinity: 1.024–1.026 SG
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Ammonia / Nitrite: 0 ppm
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Nitrate: <10 ppm
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Tank Size: Minimum 75 litres (20 gallons) for one specimen; larger systems preferred for stability
Lifespan & Size
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Size: Up to 7–10 cm (3–4 inches) leg span
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Lifespan: 2–3 years in captivity under optimal care
Reef Compatibility
Reef safe with caution. The Antler Crab is primarily a scavenger and algae grazer, contributing to tank cleanliness, but may occasionally nip at corals if underfed. Best suited for mixed reef tanks with abundant live rock or invert-focused systems where its unique shape and camouflage can be appreciated.
