Decorator Crab

Quick facts

Identity

Also known as

Sponge Crab; Decor Crab; Decorator Sponge Crab

Synonyms

Marcocoeloma trispinosum (common misspelling)

Environment

Saltwater

Native to

Caribbean, Western Atlantic, Gulf of Mexico

Habitat

Coral reefs, rubble, and live rock areas, often found among sponges and macroalgae growth where materials for camouflage are abundant

Sourcing

Wild-caught

Conservation

Not Evaluated

Care

Care level

Easy

Temperament

Peaceful

Adult size

1 – 3 in (2.5 – 7.6 cm)

Lifespan

2 – 4 yrs

Min tank

30 gal (114 L)

Growth rate

Slow

Placement

Bottom

Water

Temperature

75 – 80 °F (24 – 27 °C)

pH

8.1 – 8.4

dKH

8 – 12 dKH

Salinity

1.023 – 1.026 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

Algae, Detritus, Leftover food

Population boom risk

Low

Feeding & breeding

Diet

Omnivore

Foods

Pellets, Frozen, Algae, Live, Freeze-dried

Breeding type

Larval (brackish)

Breeding difficulty

Not bred in captivity

Sexing

No reliable external sexing traits commonly described; males may have slightly larger claws than females

Target feeding

Beneficial

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Care guide

Overview

Dresses its shell with bits of sponge, algae, and rubble collected from the rockwork, staying motionless by day and foraging only after lights out. Wild-caught and slow-growing, it suits mature reef systems with low to moderate flow and plenty of live rock for camouflage material. Reef safe with caution, as an under-decorated individual may nip soft coral or small snails.

Care

This crab does best in a mature reef tank with plenty of live rock, rubble, and access to sponge or macroalgae growth it can harvest to dress its carapace. It is mostly nocturnal, resting motionless during the day and becoming active after lights out, so daytime sightings are uncommon in a well-decorated tank. Keep temperature and salinity stable and avoid strong current, since it prefers low to moderate flow areas where it can forage undisturbed.

Feeding

Offer a mix of sinking pellets, frozen meaty foods such as mysis or chopped clam, and occasional algae sheets to cover its omnivorous needs. Feeding after lights out reduces the chance it will pick at coral tissue or small tankmates out of hunger. It also grazes naturally on detritus and biofilm found on live rock, supplementing whatever is offered directly.

Tank mates

Generally peaceful toward fish and considered reef safe with caution, since a hungry or under-decorated individual may occasionally nip at soft coral tissue, small snails, or sponge used by other tankmates. Avoid pairing with aggressive crabs, mantis shrimp, or crustacean-eating fish such as triggerfish and large wrasses. Multiple individuals can be kept together in a large enough tank with ample hiding spots to reduce conflict, particularly around molting periods.

Breeding

Breeding in home aquariums has not been documented, largely because the larvae go through a planktonic development stage that is difficult to replicate outside of a reef system. No sexual dimorphism or courtship behavior has been reliably described in aquarium settings. Most specimens in the trade are wild-collected rather than captive-produced.

Health

Molting is the most vulnerable period, during which the crab is soft-bodied and needs to redecorate its new exoskeleton quickly to avoid predation or stress. Stable calcium, alkalinity, and salinity support successful molts, and leaving shed exoskeletons in the tank lets the crab reabsorb minerals from them. Sudden parameter swings during acclimation or shipping stress are the main causes of early losses.

Sources

1. Macrocoeloma trispinosum - Decor Crab | Camouflaged Cleaner Crab for Marine Tanks
2. Sponge Crab (Marcocoeloma trispinosum) | Keys Marine Life Direct
3. Decorator Crab -TBS Farm - Tampa Bay Saltwater
4. Sponge Decorator Crab Care Guide | Top Shelf Aquatics

More Decorator crabs

Spider Decorator Crab