Spotted Trapeze Crab (Trapezia rufopunctata)

The Spotted Trapeze Crab is one of the reef hobby's most fascinating and genuinely beneficial invertebrates, and one that far too many hobbyists overlook. Its trapezoidal carapace carries a unique mottled pattern of around 100 to 200 reddish or orange spots on a white or pink background, and its eyes are a contrasting shade of vivid green, making it a strikingly beautiful little animal that is practically invisible inside the coral branches it calls home. This is a true commensal species, meaning its entire life is lived in intimate association with its host coral, and that relationship is a genuinely symbiotic one: the crab benefits from shelter and food, and the coral benefits from an active, dedicated bodyguard that works around the clock. For SPS keepers, this is one of the most rewarding and useful additions the hobby has to offer.

Why we love it

• Actively protects its host coral from predators such as crown-of-thorns starfish and other invertebrate threats, providing genuine defence that benefits the coral's long-term survival
• Constantly cleans the coral's surface of detritus and maintains water flow between branches, directly supporting coral health
• Spotted camouflage pattern is believed to help it blend into the colourful coral polyps it inhabits, making it one of the most beautifully adapted animals in the reef
• Fully reef safe and completely peaceful toward fish and other invertebrates outside its immediate territory
• A living piece of reef ecology that brings genuine scientific fascination to any SPS system

Suggested parameters

• Temperature: 24 to 26°C (75 to 79°F)
• Salinity: 1.025 to 1.026 SG
• pH: 8.1 to 8.4
• Alkalinity: 8 to 10 dKH
• Calcium: 400 to 450 ppm
• Magnesium: 1250 to 1400 ppm
• Nitrate: 5 to 20 ppm
• Phosphate: 0.03 to 0.12 ppm
• Copper-based medications are toxic to all crustaceans and invertebrates and must never be used

Care and temperament

• Difficulty: Easy, provided a suitable host coral is present
• Temperament: Peaceful toward all tankmates outside its host coral; territorial within and immediately around the host
• Reef safe: Yes, fully compatible with corals and ornamental invertebrates
• Minimum tank size: 20 gallons, provided a suitable host coral colony is present
• Primary host corals are Pocillopora and Stylophora; it will also inhabit Acropora if no pocilloporid corals are available
• Only one individual should be kept per coral colony unless a confirmed mated pair; this species is territorial within its host
• Very shy and seldom ventures out of the coral; do not expect to see much of it during the day, though pairs can occasionally be spotted at the colony's edges during feeding

Diet

The Spotted Trapeze Crab is thought to feed on particulates trapped by the coral's polyps, fallen detritus settling within the branches, and the coral's secreted mucus. In the aquarium it is entirely self-sufficient when housed with an appropriate host coral.

• No supplemental target feeding is required in a system with a healthy, established pocilloporid or Acropora host colony
• Will opportunistically consume fine particulate foods and coral mucus produced by the host during normal feeding events
• Broadcast feeding the tank as a whole provides incidental nutrition

Compatibility and tankmates

• Peaceful and fully compatible with all reef fish, corals, and ornamental invertebrates outside its immediate host coral
• Not aggressive toward neighbours but will actively and fearlessly defend its host coral against threats, including starfish and other invertebrate predators
• Avoid aggressive fish species such as triggers or large wrasses that may target small crustaceans
• Keep one per coral colony unless a known mated pair; a second individual introduced to an occupied colony will be evicted or fought

Health and acclimation notes

The Spotted Trapeze Crab is easy to keep when its one non-negotiable requirement is met: a suitable, established host coral that is large enough to shelter it comfortably. Without an appropriate host colony already in the tank, this species cannot thrive and will become stressed and exposed. It lives harmoniously within colonies of branching corals and contributes to coral health by keeping the surface clean of detritus and defending against small parasites and predatory invertebrates. Drip acclimation is recommended as with all invertebrates, and copper-based medications must never be used in any system housing crustaceans.

What you are buying

• You will receive: 1 Spotted Trapeze Crab (Trapezia rufopunctata)
• Carapace colouration is white to pale pink with 100 to 200 reddish-orange spots and vivid green eyes; colouration may vary slightly between individuals and collection regions
• Size at time of sale can vary; maximum carapace width is approximately 2 to 2.5 cm

Drip acclimation is recommended. A suitable established host coral must be present before introduction. Copper-based medications must never be used in any system housing this animal.