Garmard's Hermit Crab

Quick facts

Identity

Also known as

Gaimard's Hermit Crab; Blue-Eyed Hermit Crab

Synonyms

Calcinus terrae-reginae; Pagurus gaimardii

Environment

Saltwater

Native to

Indo-Pacific, Indian Ocean, Red Sea, Australia, Fiji, Japan, Taiwan, Philippines, Indonesia, Hawaii

Habitat

Intertidal and subtidal rocky and coral reef areas, tide pools, and shallow reef flats from the intertidal zone down to about 40 m depth.

Sourcing

Wild-caught

Conservation

Not Evaluated

Care

Care level

Easy

Temperament

Peaceful

Adult size

0.5 – 1.2 in (1.3 – 3 cm)

Lifespan

1 – 3 yrs

Min tank

5 gal (19 L)

Growth rate

Slow

Placement

Bottom, Rock & glass

Water

Temperature

74 – 82 °F (23 – 28 °C)

pH

8.0 – 8.4

dKH

8 – 12 dKH

Salinity

1.023 – 1.025 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

Algae, Frozen, Pellets

Breeding type

Larval (brackish)

Breeding difficulty

Not bred in captivity

Sexing

Sexes are not visually distinguishable without close examination; not typically sexed in the hobby.

Target feeding

Beneficial

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Care guide

Overview

Calcinus gaimardii is a small reef hermit crab showing brown, orange, and red tones with pale blue eyestalks, rarely exceeding 1.2 inches. It scavenges algae and detritus over rock and substrate mainly at night, borrowing shells rather than building its own protection. Easy to keep in nano reefs, it occasionally competes with snails for shells, so extra empty ones should stay on hand.

Care

This dwarf hermit crab adapts readily to nano and standard reef tanks alike, spending most of its time picking over rockwork and substrate. It tolerates a wide range of typical reef parameters and does not require special lighting or flow, making it one of the easier invertebrates to keep. Because it molts and grows steadily, it needs a steady supply of empty shells slightly larger than its current one on hand at all times.

Feeding

In the wild it grazes on algae film and scavenges organic matter among rubble and rock, and in captivity it will eat whatever sinks to the substrate. Offer sinking pellets, frozen mysis or brine shrimp, and let it forage on nuisance algae and detritus between feedings. It rarely needs targeted feeding if kept in an established tank with adequate biofilm and algae growth.

Tank mates

It generally ignores fish and corals but can become a problem for snails, occasionally attacking and killing them to claim a preferred shell. Keeping a stock of empty shells of varying larger sizes greatly reduces this behavior. It coexists well with other peaceful reef inhabitants and other hermit species as long as shell competition is minimized.

Breeding

Reproduction has not been achieved in home aquariums, as the larvae require a planktonic marine environment to develop. Wild populations reproduce via broadcast-released larvae that drift and settle after passing through several zoeal stages. Hobbyists should not expect to breed this species under normal reef tank conditions.

Health

Stress from being wedged into an ill-fitting or damaged shell is the most common issue, sometimes leading to prolonged hiding or failure to molt properly. Sudden salinity or temperature swings can also cause problems, so drip acclimation is recommended for new arrivals. Otherwise this species is hardy and rarely afflicted by disease in a well-maintained system.

Sources

1. Calcinus gaimardii - Marinelife
2. Salty Underground: Blue Eye Hermit Crab (Calcinus gaimardii)
3. Calcinus gaimardii Gaimard's Hermit Crab - Reeflex
4. Hermit crabs Calcinus of the world (Anomura: Diogenidae) - Calcinus gaimardii

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