Spider Decorator Crab

Quick facts

Identity

Also known as

Camposcia Decorator Crab

Synonyms

Camposcia hirsuta

Environment

Saltwater

Native to

Red Sea, East Africa, Indo-West Pacific, Japan, Australia

Habitat

Coral reefs, rubble fields, lagoons, and mangrove roots rich in algae and sponges, from shallow water to over 200 m depth.

Sourcing

Wild-caught

Conservation

Not Evaluated

Care

Care level

Easy

Temperament

Semi-Aggressive

Adult size

1 – 4 in (2.5 – 10 cm)

Lifespan

3 – 5 yrs

Min tank

26 gal (98 L)

Growth rate

Slow

Placement

Bottom, Rock & glass

Water

Temperature

72 – 78 °F (22 – 26 °C)

pH

8.1 – 8.4

dKH

8 – 12 dKH

Salinity

1.023 – 1.025 SG

Flow

Low-Moderate

Behavior & compatibility

Social

Solitary

Aggression to own kind

Low

Active

Night

Reef safe

With caution

Invert safe

With caution

Shrimp safe

With caution

Clean-up role

Detritus, Leftover food, Algae

Population boom risk

Low

Feeding & breeding

Diet

Carnivore

Foods

Frozen, Live, Freeze-dried, Algae

Breeding type

Larval (brackish)

Breeding difficulty

Not bred in captivity

Sexing

Not typically distinguishable by hobbyists; males may have slightly larger claws, but sexing is not commercially relevant.

Target feeding

Beneficial

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Care guide

Overview

Reaching roughly 1 to 4 inches across a spindly, tan-brown carapace, this crab builds a living camouflage coat from sponge bits, algae, and rubble picked off the rockwork. By day it sits motionless among live rock, emerging after lights-out to forage detritus and target-fed meaty scraps. A mature reef with ample debris and tight hiding spots suits it better than a bare or frag-heavy system.

Care

This spider crab spends most daylight hours motionless, tucked among rock and rubble, and becomes active only after the lights go down. It relies on loose material in the tank, such as macroalgae, sponge fragments, and coral rubble, to decorate its carapace and legs, so a mature reef with plenty of live rock and debris suits it far better than a bare tank. Stable calcium, magnesium, and iodine levels support successful molting, and a secure hiding spot is important while the new shell hardens. It does poorly with copper-based medications, so these should never be used in a tank housing this crab.

Feeding

Camposcia retusa is an opportunistic scavenger that will pick at leftover fish food and detritus, but a few weekly target feedings of chopped clam, shrimp, fish, or mysis keep it from turning to coral tissue or slow-moving invertebrates. Offering food directly after the lights go out matches its nocturnal foraging habit and reduces competition with diurnal tankmates. It also grazes algae and biofilm off rock and rubble surfaces during its nightly wanderings.

Tank mates

It generally ignores fish and larger invertebrates, making it compatible with most peaceful reef community members. The main caution concerns soft corals, zoanthids, and sponges, since it may snip off pieces of these to attach to its own body for camouflage, occasionally stripping small colonies. In frag-heavy or high-value coral tanks this habit can be a nuisance, though in larger display tanks with hardy soft corals the clipping can actually help spread coral fragments around the aquarium.

Breeding

Reproduction in home aquariums essentially does not happen, since the larvae pass through several planktonic zoeal stages that are almost always lost to filtration or predation. Research institutions have reared larvae under controlled conditions using live prey such as Artemia nauplii and copepods at specific salinities, but this is well beyond typical hobbyist capability. All specimens in the trade are wild-caught rather than captive-bred.

Health

Molting is the riskiest period in this crab's life in captivity, since it is vulnerable and defenseless until the new exoskeleton hardens, so rockwork with tight crevices for cover is important. Copper exposure, even at levels tolerated by fish, is lethal and must be avoided entirely. Sudden swings in salinity or pH during acclimation can also stress newly imported specimens, so slow drip acclimation is recommended.

Sources

1. Decorator crab care: tank size, temperature and tankmates · TankBud
2. Spider Decorator Crab (Camposcia Decorator Crab): Saltwater Aquarium Invertebrates – LiveAquaria
3. CRAB - SPIDER DECORATOR Camposcia retusa - Aquatics Unlimited
4. Development of captive rearing techniques for decorator crab, Camposcia retusa, for marine aquarium trade

More Decorator crabs

Decorator Crab