Blue leg hermit crab (Clibanarius tricolor) care guide

Group
Other invertebrates
Other names
Dwarf blue leg hermit crab, Blue-legged hermit crab, Clibanarius brachyops
Family
Diogenidae
Origin
Caribbean Sea; shallow rocky areas
Water
saltwater
Maximum size
2.5 cm
Temperature
22–26°C
pH
8.1–8.4
Hardness
SG 1.020–1.025, dKH 8–12
Minimum tank
40 litres
Care level
beginner
Temperament
peaceful
Reef safe
with_caution

Care

The blue leg hermit crab is a tiny Caribbean hermit crab, about 2–2.5 cm, with bright blue legs banded with red at each joint. Males are larger than females. It lives in old snail shells and carries its home with it. Clean-up crew: one of the most popular reef clean-up animals. It eats hair algae and cyanobacteria, reaching into small crevices in rock, and it scavenges detritus, dead animals and leftover food. It also sifts sand, which helps keep the surface clean and aerated. A common guide is about one per 4–8 litres in a tank with plenty of algae (general guidance, not from a source); with too many they run out of food. Spare shells: hermit crabs must move into larger shells as they grow. Always provide a few empty shells of slightly larger size than the ones they wear. Without spare shells, or when food is short, they will attack and kill snails to take their shells, and they fight each other over shells, flipping a rival over and shaking it out of its shell. Behaviour: in the wild they rest in groups by day and feed from dusk through the night, moving in groups. In the aquarium they are active and entertaining. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most invertebrates. Never dose copper in a tank holding this animal, and check fertiliser and medicine labels before use. Sources: LiveAquaria (liveaquaria.com/products/dwarf-blue-leg-hermit-crab-tiny); Wikipedia (en.wikipedia.org/wiki/Clibanariustricolor). Checked October 2026.

Diet

Scavenging omnivore: hair algae, cyanobacteria, film algae, detritus, dead plants and animals and leftover food. Supplement with dried seaweed, sinking pellets or small frozen foods if algae runs short, which also reduces attacks on snails.

Breeding

Sexes are separate; males are larger. Females carry eggs under the abdomen inside the shell and release planktonic larvae, which need marine water and plankton and do not survive in home aquariums.

Compatibility and tank mates

Peaceful with fish and corals; reef compatible. Marked with caution because it kills snails (turbos, ceriths, nassarius, margaritas) for their shells and may pick at very small invertebrates, and hungry crabs can disturb small polyps. Larger crabs, wrasses, triggers and puffers eat it. Provide spare shells.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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