Dwarf Hermit Crab – Calcinus sp.

Common name: Dwarf Hermit Crab

Scientific name: Calcinus sp.

Origin: Indo-Pacific (varies by species)

Adult size: 2–4 cm (depending on species)

Temperament: Generally peaceful

Minimum tank size: 40 L+

Reef safe: Yes (with caution)

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Overview

Hermit crabs of the genus Calcinus are popular members of the reef aquarium clean-up crew. These small, active crustaceans help control algae and consume leftover food, contributing to overall tank maintenance.

Species within this genus may vary slightly in coloration, but many display attractive blue, red, orange or banded legs.

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Behavior & Compatibility

Generally peaceful but opportunistic.

May occasionally compete with other hermits for shells. Providing spare empty shells of various sizes helps reduce aggression.

Compatible with most reef fish and invertebrates.

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Feeding

Omnivorous scavengers that consume:

• Microalgae

• Film algae

• Leftover food

• Detritus

Supplement feeding with small pellets or algae-based foods if natural algae is limited.

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Care Notes

• Provide plenty of rockwork and hiding spaces

• Keep stable reef parameters

• Offer spare shells to prevent shell fights

A practical and active addition to reef aquariums, helping maintain cleanliness while adding movement and color to the tank.