Rusty Guard Crab care guide
Rusty Guard Crab (Trapezia ferruginea) — minimum tank 100 L, temperature 24-26 °C, pH 8.1-8.4.
Compiled by Aquairi from published sources · Published · Updated
Overview
Rusty Guard Crab (Trapezia ferruginea) is a coral guard crab of the family Trapeziidae, listed in the Aquairi knowledge base as an advanced-level species. Rust-red small crab living between coral branches as a mutualistic guard. Defends host coral against predators.
Taxonomy
- Family: Trapeziidae
- Genus: Trapezia
- Scientific name: Trapezia ferruginea
- Common synonyms: Red Coral Crab
Habitat
Trapezia guard crabs (family Trapeziidae) are small reef crabs that live obligately among the branches of pocilloporid and acroporid corals. They defend the host coral against predators such as crown-of-thorns sea stars in exchange for shelter and mucus food. In the Aquairi knowledge base this species is recorded from Indo-Pacific.
Tank requirements
- Minimum tank volume: 100 L (26.4 US gal)
- Adult size: 1-2 cm
- Temperature: 24-26 °C (75-79 °F)
- pH: 8.1-8.4
- GH: 8-12 °dGH
- KH: 8-12 °dKH
- Salinity (specific gravity): 1.024-1.026
- Lifespan: 1-3 years
Diet
The species is an omnivore, taking a wide range of foods including meaty frozen foods, sinking pellets and detritus gathered from the rockwork.
Compatibility
The Aquairi knowledge base lists this species as peaceful. Suitable tank mates include SPS corals. It should be kept away from Aggressive fish. It lives obligately within a host Pocillopora or Acropora colony and is best added together with the coral.
Breeding
Breeding requires an extended planktonic larval stage in open water before the young settle, which makes captive reproduction very difficult and rarely accomplished in home aquaria. Most specimens in the hobby are wild-collected.
Breeding the Rusty Guard Crab (Trapezia ferruginea)
Overview
Trapezia ferruginea is a coral guard crab of the family Trapeziidae that lives in obligate association with Pocillopora corals. Like other Trapezia, it feeds on coral tissue and mucus and grazes polyp-tip lipids, while defending its host from corallivores such as the crown-of-thorns seastar Acanthaster planci. Field studies show corals are attacked far more often once guard crabs are removed.
Sexing
A single mating pair of a given Trapezia species typically occupies each coral colony, so a resident male-female pair on one coral head is the practical indicator of sexes. Females are recognized by a brooded egg mass carried under the abdomen.
Conditioning
A healthy Pocillopora host providing mucus and lipids is the natural conditioning environment for a resident pair. No documented protocol reliably induces or completes reproduction in a home reef, because the larvae are planktonic and cannot be reared in a closed display.
Breeding Setup
No practical home breeding setup exists. A resident pair may produce broods on the host coral, but the female releases planktonic larvae into the water column that require open-water plankton and stable parameters not available in a closed system.
Spawning & Larvae
Fertilized eggs are brooded by the female and hatch into planktonic zoea larvae that develop through successive molts before settling, after which juveniles must locate a suitable host coral. This planktonic development combined with obligate host dependence makes captive rearing impractical.
Common Challenges
- Planktonic larvae are removed by filtration and skimming.
- Larvae require continuous planktonic food through multiple stages.
- Settling juveniles must find a compatible host coral.
- Only one pair occupies a coral head, limiting stocking.