Scarlet reef hermit crab with bright red legs

KNOWLEDGE, CULTIVATED.

Cleanup Crew

Choose the right workers for the job: algae grazers, leftover-food scavengers and sand-surface feeders have different needs.

Useful: a practical addition when properly fed. Caution: specialist care or compatibility risks. Start small and add only what your reef can sustain; cleanup animals recycle waste rather than exporting nutrients. Maintain filtration and routine cleaning.

Adult sizes are approximate: snail sizes describe shells, crab sizes state the measurement used, and star sizes include arms. Confirm the supplier’s species, acclimate to matched conditions and quarantine appropriately; do not use coral dips on cleanup animals.

Written by Christian, Signature FragsLast reviewed:

Urchins

All cleanup crew
Tuxedo urchin — Mespilia globulus

Tuxedo urchin reference photograph.

Tuxedo urchin

Caution

Mespilia globulus

Effective grazer; also eats coralline and carries loose objects.

Quick ID
Rounded body with broad blue bare bands alternating with short spine-covered areas.
Typical adult size
About 5 cm body diameter; spines increase overall width.
Useful work
Grazes algae films and short growth over rock and glass.
Feeding & care
Secure frags, guard exposed intakes and offer nori or herbivore food when grazing is insufficient.
Best fit
Mature reefs with enough surface growth; avoid where preserving all coralline is essential.
Watch out for
Can strip coralline and carry frags, rubble or shells. Starvation is possible in very clean reefs.
Research sources
Halloween / collector urchin — Tripneustes gratilla

Halloween / collector urchin reference photograph.

Halloween / collector urchin

Caution

Tripneustes gratilla

A larger grazer requiring generous space and food.

Quick ID
Short spines, often orange/white patches, and a habit of covering itself with loose material.
Typical adult size
About 10 cm body diameter; overall width with spines is larger.
Useful work
Grazes films, turf and some macroalgae across rock.
Feeding & care
Secure rock and frags; supply seaweed if natural algae is insufficient. Do not pull it off surfaces by its spines.
Best fit
Larger established reefs with plenty of grazing area.
Watch out for
Can move frags and reduce desirable macroalgae or coralline. Too much crew can exhaust its food supply.
Research sources
Close-up of coral tentacles in purple, pink, blue and green

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