Common name: Red-spotted Coral Crab

General Information

The Red-spotted Coral Crab, scientifically known as Trapezia rufopunctata, is a fascinating species of crab that has captivated reef enthusiasts with its unique appearance and symbiotic behavior. This small, colorful crab is easily recognized by its cream-colored body adorned with vibrant red spots, making it a striking addition to any reef aquarium. Native to the Indo-Pacific region, this species is often found living among branching corals, particularly those of the genus Pocillopora.

What makes Trapezia rufopunctata particularly interesting is its role as a protector of its coral host. In the wild, these crabs defend their host coral from predators such as Acanthaster planci and other threats. In return, the coral provides the crab with shelter and a steady supply of mucus and detritus for food. This mutualistic relationship is a prime example of the intricate symbiosis found in coral reef ecosystems.

Care

Caring for Trapezia rufopunctata in a home aquarium requires a reef setup with healthy branching corals, particularly Pocillopora species, as these corals serve as their natural hosts. The presence of these corals is essential for the crab's well-being, as it relies on the coral for both shelter and sustenance. A well-established reef tank with stable water parameters and moderate to strong lighting is ideal for maintaining both the coral and the crab.

These crabs are relatively hardy and can adapt to a range of reef tank conditions, provided their host coral is thriving. Regular monitoring of coral health is crucial, as the crab's survival is closely tied to the condition of its host. Avoid introducing species that may prey on the crab or damage its coral host, such as certain wrasses or butterflyfish.

Diet and Feeding

In the wild, Trapezia rufopunctata feeds on the mucus and detritus produced by its coral host. In captivity, this diet can be supplemented with finely chopped seafood, plankton, or other small meaty foods. However, the majority of its nutritional needs will be met through its symbiotic relationship with the coral.

Feeding frequency is minimal, as the crab primarily relies on its host coral for sustenance. Occasional supplementation can be provided to ensure optimal health, particularly if the coral is not producing sufficient mucus or detritus.

Behavior and Compatibility

Red-spotted Coral Crabs are peaceful and highly specialized, spending most of their time within the branches of their host coral. They are not aggressive towards other tank inhabitants but may exhibit territorial behavior if their coral is threatened. This behavior is generally limited to defending their host and does not extend to other areas of the tank.

These crabs are compatible with a wide range of reef-safe fish and invertebrates. However, care should be taken to avoid housing them with species that may prey on small crustaceans or damage their coral host. Keeping multiple Trapezia crabs in the same tank is possible, but they should each have their own coral host to avoid competition.

Symbiosis

The symbiotic relationship between Trapezia rufopunctata and branching corals like Pocillopora is one of its most remarkable traits. The crab defends the coral from predators and helps keep it clean by removing debris and detritus. In return, the coral provides the crab with shelter and a source of food in the form of mucus and detritus. This mutualistic relationship is not only fascinating but also beneficial for the health of the coral, as the crab's presence can deter coral predators and reduce stress on the coral.

Health and Common Issues

Red-spotted Coral Crabs are generally hardy, but their health is closely tied to the condition of their host coral. If the coral begins to decline due to poor water quality, inadequate lighting, or predation, the crab's survival will also be at risk. Maintaining stable water parameters and providing a suitable host coral are the most important factors in ensuring the crab's well-being.

When selecting a Trapezia rufopunctata, look for active individuals with intact limbs and vibrant coloration. Avoid crabs that appear lethargic or have visible signs of injury. Regular monitoring of both the crab and its host coral is essential to catch and address any issues early.

Habitat

In the wild, Trapezia rufopunctata is found in coral reefs across the Indo-Pacific, from the Red Sea to the central Pacific. It inhabits branching corals, particularly those of the genus Pocillopora, at depths ranging from shallow lagoons to deeper reef slopes. These crabs thrive in warm, clear waters with abundant coral growth and minimal sedimentation.

To replicate their natural habitat in captivity, provide a well-established reef tank with healthy branching corals and stable water conditions. Moderate to strong water flow and lighting are essential for the health of the coral host, which in turn supports the crab.