A tiny, inexpensive hermit crab with blue legs banded in red and orange, sold by the dozen as nano-reef cleanup crew. It is an energetic algae and detritus grazer but is notorious for killing snails to steal their shells.
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Very small; usually under 1 in (1-2 cm) including shell.
Lifespan
1–4 years
Social needs
group
Native region
Western Atlantic and Caribbean, including Florida, the Bahamas, and the West Indies
Origin
New World
Climate
🌴 Tropical
Water type
🌊 Marine
Family
Diogenidae
Genus
Clibanarius
Part of the Hermit Crabs
Shell-dwelling crustaceans kept as scavenging cleanup crew. Marine reef hermits graze algae, cyanobacteria, and detritus across live rock and sand, staying small and mostly peaceful; provide assorted empty shells so growing crabs can upgrade homes instead of attacking snails.
From the minimum an animal needs to be kept humanely, up to the ideal setup. Bigger is almost always better — minimums are floors, not targets.
Photo coming soon
Minimum
Reef aquarium
20 gal (≈ 76 L) reef
Clibanarius tricolor is a marine reef cleanup-crew hermit (NOT a land hermit). Keep in groups of ~1 per 5 gal in a reef tank with rockwork. Provide spare shells of increasing sizes so they can upgrade. Stable 1.025 salinity.
Photo coming soon
Recommended
Reef with diverse CUC
30–55 gal reef, varied shells
A 30+ gal reef with extensive rockwork, sand bed, and a variety of empty shells. Blue-legs are peaceful but will kill snails for shells if shells are scarce.
Photo coming soon
Ideal
Mature display reef
55+ gal mature reef
A larger mature reef with a balanced cleanup crew and abundant spare shells. Generous space lets blue-legs forage natural detritus.
Life & growth stages
How this animal changes through its life — each stage often has its own care, diet and space needs.
Photo coming soon
Larva
Most marine invertebrates hatch into microscopic planktonic larvae (such as the zoea of crustaceans or the bipinnaria/veliger of echinoderms and mollusks) that drift and feed in the water column. The larva looks nothing like the adult and undergoes major reorganization.
Photo coming soon
Juvenile
After settling out of the plankton, the juvenile takes on a recognizable miniature of the adult body plan — a tiny shell, a small star, or a translucent shrimp. Crustaceans grow by molting, shedding the exoskeleton to enlarge.
Adult
Adults reach full size and reproductive maturity with the species' mature shell, shape, or coloration. Many continue to molt or grow throughout life, and some show sex differences in size or claw/appendage shape.
Habitat & enclosure
Ideal for nano and larger reef tanks from about 38 L (10 gal); their small size suits even pico setups. Maintain standard reef chemistry: temperature 24-27 C (75-80 F), pH 8.1-8.4, specific gravity 1.023-1.026, with stable alkalinity, calcium, and zero copper.
They need live rock with abundant nooks for grazing and molting, plus a sand bed to sift. Lighting and flow are not critical to the crab itself; any reef-appropriate light and gentle-to-moderate flow work since they live off algae and biofilm rather than photosynthesis.
Substrate
Live rock provides grazing surface and molt shelter, while a fine aragonite sand bed supports detritus sifting. Provide many empty shells in graduated sizes — this is the single best way to reduce snail predation.
Equipment & setup
Live rock biofiltration, a stable heater, and a protein skimmer cover the essentials for the marine system they live in. No dedicated lighting is required; modest powerhead flow keeps detritus available without blasting the small crabs around.
Diet
An opportunistic omnivore and detritivore that grazes hair algae, film algae, cyanobacteria, and uneaten food across rock and sand. In clean tanks it readily takes dried seaweed, pellets, and small meaty scraps. Keep dissolved calcium adequate for molting, and ensure enough food so crabs don't turn predatory on snails or each other.
Behavior & temperament
Active and mostly reef-safe toward corals and fish, but opportunistically aggressive: it will pull snails (and rival hermits) from their shells to claim a bigger home. Best kept in groups, which mirrors their natural gregarious behavior, but always with a generous surplus of empty shells. Compatible with most reef cleanup crews as long as shell supply is high.
Health
Most losses stem from copper toxicity, salinity swings, and starvation in overly clean tanks. Like all hermits they are vulnerable while molting and may appear dead; never discard a motionless crab or empty shed prematurely. Shell theft and fighting spike when empty shells are scarce, so shell shortage is effectively a health/welfare issue.
Tips, DIY & hacks
Drip-acclimate slowly and add a pile of assorted empty snail shells to curb their shell-stealing habit. Cheap and effective for clearing hair algae and cyanobacteria, but stock conservatively alongside snails and offer extra food in algae-poor tanks. Inspect new arrivals for the correct number of legs and good vigor.
