Red-spotted Coral Crab
Trapezia rufopunctata
A stunning symbiotic marine crab that lives exclusively within Pocilloporid branching corals, featuring a pink or white body densely covered in large red spots.
Water Temperature
22 - 28 °C
pH Value
8.1 - 8.4
Water type
Marine
Invertebrate type
Marine crab
Adult size
3.5 cm
Minimum group
>= 1
KH
8 - 12 dKH
Ecological role
Symbiont
Copper sensitivity
High
Species description
Geographical Origin and Habitat: Widely distributed throughout the tropical Indo-Pacific, from the Red Sea and East Africa to Hawaii, Polynesia, and the Galapagos. Found strictly within live colonies of branching corals (Pocillopora or Acropora).
Taxonomy: Member of the family Trapeziidae. Features a smooth, shiny trapezoidal carapace measuring about 3-4 cm in width. Legs have curved tips adapted for clinging tightly to coral branches. Grows to 3.5 cm.
Social Behavior: Mutualistic symbiont. Actively defends its host coral from predators (like the Crown-of-Thorns starfish, Acanthaster planci) by pinching their tube feet. Typically lives in stable male-female pairs.
Coloration and Sexual Dimorphism: Spectacular color pattern of a white, yellow, or pinkish-cream base body covered in large, regularly spaced bright red or reddish-orange spots. No visible sexual dimorphism.
Care, breeding and tankmates
Tank Setup: Must be kept in a mature reef tank of 20 gallons or larger containing at least one healthy colony of branching coral (Pocillopora or Acropora). Does not require empty shells.
Diet and Feeding: Feeds on coral mucus and organic detritus trapped between the coral polyps. In aquariums, it also catches suspended food like mysis or brine shrimp from the water column.
Water Quality: Reef parameters. Salinity SG 1.021-1.025, pH 8.1-8.4, temperature 22-28°C. Highly sensitive to copper treatments, elevated nitrates, and sudden salinity drops.
Compatibility and Tankmates: 100% reef-safe. Mutualistic protector of its host coral. Compatible with peaceful reef fish. Avoid predatory tankmates (e.g. hawkfish, wrasses, or groupers).
Aquarium Breeding: Microscopic larval stages are pelagic and complex, and do not survive standard home aquarium filtration systems.
Risks and Diseases: Direct dependence on the host coral; if the coral host dies, the crab will experience high stress and likely perish. Requires stable calcium and iodine for molting.
Geographic origin and distribution
Widely distributed throughout the tropical Indo-Pacific, from the Red Sea and East Africa to Hawaii, Polynesia, and the Galapagos. Found strictly within live colonies of branching corals (Pocillopora or Acropora).
Origin
Cosmopolitan or introducedAfrica and MadagascarTropical oceans and reefs
Invertebrate profile
- Diet
- Photosynthetic
- Feeds on coral mucus, trapped detritus, and small plankton.
- Ecological role
- Symbiont
- Forms a symbiotic relationship with SPS corals. Defends the host from predators.
- Adult size
- 3.5 cm
- Jump risk
- Yes
- Strictly associates with coral branches and does not jump.
- Shock sensitivity
- Medium
- Requires pristine water conditions similar to its SPS host.
- Calcium and minerals
- Medium
- Needs stable calcium levels similar to what its host coral requires.
- Molting
- Yes
- Like all crustaceans, it sheds its exoskeleton to grow. During this vulnerable molting period, it remains highly secretive and hides deep within the branches of its host Pocillopora or Acropora coral for protection.
- Reproduction
- Bubble nest builder
- Often found in pairs that breed within the coral. Larvae enter the water column.
- Compatibility & tankmates
- Reef safe
- Completely reef safe and highly beneficial. This territorial guard crab actively protects its host SPS corals from predators like crown-of-thorns starfish and keeps the coral clean. Best kept as a single mated pair per colony.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
