Blue Eye Hermit Crab (Calcinus laevimanus)

The Blue Eye Hermit Crab is one of the most attractive and useful small hermit crabs available for the reef aquarium. Its otherwise dark legs are dressed in white or orange bands, and its long eyestalks are a brilliant blue that fades into an orange-tinged upper half, giving this little crab a colour combination that punches well above its size. Also known as the Dwarf Zebra Hermit Crab, the Hawaiian Reef Hermit, and the Left-Handed Hermit Crab, this species has an enlarged left claw that it uses to block the entrance to its shell when threatened by a predator, a clever built-in defence mechanism that makes it hardier and more self-sufficient than many other small reef hermits. What it lacks in size it more than makes up for in cleaning performance and reef compatibility.

Why we love it

• Brilliant blue and orange eyestalks with boldly banded black and white legs make this one of the most visually striking small hermits in the hobby
• Consumes hair algae, film algae, detritus, uneaten fish food, and cyanobacteria, covering a broad range of common reef nuisances
• Fully reef safe and peaceful with corals, fish, and most ornamental invertebrates
• Small adult size makes it an excellent addition to nano aquariums as well as larger systems
• Hardy, active, and endlessly entertaining to watch as it explores the rockwork

Suggested parameters

• Temperature: 24 to 26°C (75 to 79°F)
• Salinity: 1.025 to 1.026 SG
• pH: 8.1 to 8.4
• Alkalinity: 8 to 10 dKH
• Calcium: 400 to 450 ppm
• Magnesium: 1250 to 1400 ppm
• Nitrate: 5 to 20 ppm
• Phosphate: 0.03 to 0.12 ppm
• Copper-based medications are toxic to all invertebrates and must never be used

Care and temperament

• Difficulty: Easy
• Temperament: Peaceful toward fish, corals, and most invertebrates; all hermit crabs are capable of killing snails for their shells, and this is something to be mindful of when stocking your cleanup crew
• Reef safe: Yes, fully compatible with corals and sensitive invertebrates
• Minimum tank size: 20 gallons; suitable for nano systems
• Best added to mature, well-established aquariums where a plentiful source of marine algae is already present
• Active among rocks and rubble, constantly exploring in search of organic matter
• A selection of empty shells in graduated sizes must always be available so this crab can move up as it grows

Diet

The Blue Eye Hermit Crab is primarily herbivorous with scavenging tendencies that make it a versatile and effective cleanup crew member.

• Grazes naturally on algae, biofilm, and cyanobacteria growing on rockwork and substrate throughout the day
• Scavenges detritus and uneaten fish food from the sandbed and rock surfaces
• If there is insufficient algae present in the aquarium, supplement with dried seaweed or nori to prevent starvation
• Will also accept quality sinking pellets and algae-based prepared foods as supplemental feeding
• No target feeding necessary in most established reef systems with healthy algae growth

Compatibility and tankmates

• Excellent with all reef fish, corals, and most ornamental invertebrates
• Avoid housing with larger crabs, aggressive hermit crabs, or fish with powerful jaws that might attack it or target its shell
• Can be kept in groups; multiple individuals work well together in a reef system provided sufficient space and food are available
• Avoid triggerfish, pufferfish, and large aggressive wrasses that may target small invertebrates
• Keep an eye on snail populations; provide plenty of empty shells to reduce the likelihood of snail predation

Health and acclimation notes

The Blue Eye Hermit Crab is a hardy, low-maintenance species that settles into reef systems quickly and gets to work almost immediately. Drip acclimation is recommended, as with all invertebrates, to avoid osmotic shock from rapid salinity changes. The most important ongoing care requirement is maintaining a supply of appropriately sized empty shells at all times. A hermit crab left without a suitable shell to move into during growth is a stressed and vulnerable animal. Regular water changes help maintain the mineral levels that support healthy exoskeleton development, and copper-based medications must never be used in any system housing this or any other invertebrate.

What you are buying

• You will receive: 1 Blue Eye Hermit Crab (Calcinus laevimanus)
• Shell colour and leg banding can vary slightly between individuals; the brilliant blue lower eyestalk and enlarged left claw are the key identifying features of this species

Drip acclimation is recommended. Empty shells in graduated sizes must be maintained in the system. Copper-based medications must never be used in any system housing this animal.