Calcinus elegans
Source: Kasper Hareskov Tygesen
Calcinus elegans
Source: Kasper Hareskov Tygesen


Latin name Calcinus elegans
Common name Electric Blue Hermit Crab
Family Paguroidea - Calcinus
Origin East Indian Ocean, West Indian Ocean, Australia, Indonesia
Max length 5 cm (2.0")

As aquarium fish

Minimum volume 50 l (13 gal)
Hardiness Hardy
Suitable for aquarium Suitable for most aquarium
Reef safe Always reef safe
Aggressiveness Mostly peaceful but might be aggressive towards similar species


  • Small crustaceans (Krill, mysis, artemia...)
  • Detritus
  • Microalgae (Eg. spirulina)
  • Macroalgae (Eg. seaweed / nori)

Number of fish

A good many of these fish can exist in the same aquarium, but they will kill each other without insufficient space and/or food.

Count therefore on about 40 gal (150 liters) each, if one desires several in one tank.

Family description (Paguroidea)

Hermit crabs can be lots of fun, but are not particularly useful in the tank.
They are generally easy to keep, but not all species are algae eaters, some eat mostly zooplankton off the rocks.

Remember that they require new shells to grow.

References and further reading

About references

James W. Fatherree. 2010. Aquarium Invertebrates: Crabs in the Marine Aquarium - Advanced Aquarist - (English)
Ronald L. Shimek. 2004. Marine Invertebrates (PocketExpert Guide) - TFH Publications / Microcosm Ltd. - (English)
Bob Fenner. Crabs For Marine Aquariums? Part 1, Part 2, Part 3 - Wet Web Media - (English)

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