Blue Leg Hermit Crab
Calcinus elegans
Also known as: blue-knuckled hermit, electric blue hermit crab, elegant hermit, elegant hermit crab
Vivid blue legs and a big appetite for algae make this hermit a reef workhorse.
About
The blue leg hermit crab (Calcinus elegans) is one of the more recognizable small hermit crabs in the saltwater hobby, thanks to its bold coloration. Bright blue legs banded with black give it an almost electric appearance that stands out against rock and sand alike. It originates from the Indo-Pacific, where it lives in shallow, tropical coastal waters no deeper than about 30 feet, scrambling across benthic substrate in search of algae and organic debris. In the aquarium it earns its place as a genuinely useful cleanup crew member, grazing on filamentous algae, cyanobacteria, and detritus that would otherwise accumulate on rock surfaces and the sandbed. Like all hermit crabs it will periodically need a larger shell as it grows, so keeping a selection of appropriately sized empty shells in the tank is good practice. A crab that can't find a suitable shell may evict a neighbor, sometimes with fatal consequences for the evicted party. Generally peaceful with fish and corals, it can occasionally scuffle with other hermit crabs over shell real estate. This species is best suited to a reef or FOWLR setup with an established algae growth, and while not difficult to keep, it does best with stable water quality and an attentive keeper.
Similar species
Other invertebrate you might consider
Good tank mates
Species that tend to coexist peacefully with Blue Leg Hermit Crab
From the same region
Share the same natural habitat. Great for a biotope-themed tank
Frequently asked questions
- How big does the Blue Leg Hermit Crab get?
- The Blue Leg Hermit Crab reaches about 1–2" as an adult.
- What size tank does the Blue Leg Hermit Crab need?
- A minimum of 30 gallons is recommended for the Blue Leg Hermit Crab.
- What water parameters does the Blue Leg Hermit Crab need?
- The Blue Leg Hermit Crab does best with a temperature of 72–78°F, a pH of 8.1–8.4, hardness around 8–12 dGH.
- Is the Blue Leg Hermit Crab aggressive?
- The Blue Leg Hermit Crab is generally peaceful and suits a community tank with similarly calm tankmates.
- What does the Blue Leg Hermit Crab eat?
- The Blue Leg Hermit Crab is a herbivore. It needs a plant-based diet such as algae, blanched vegetables, or spirulina-based foods.
- How long does the Blue Leg Hermit Crab live?
- With good care, the Blue Leg Hermit Crab typically lives 4-5 years.
- Is the Blue Leg Hermit Crab reef safe?
- The Blue Leg Hermit Crab is generally considered reef safe.