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    Hermit crab

    Blue leg hermit crab

    Clibanarius tricolor

    Blue leg hermit crab (Clibanarius tricolor)
    Photo: RevolverOcelot, CC BY-SA 3.0, via Wikimedia Commons
    Group
    Hermit crab
    Care level
    Beginner
    With corals
    Reef safe with caution

    What does the blue leg hermit crab do in a reef tank?

    Algae and scavenged food; small size lets it reach rock crevices

    With corals: Mostly, with caution

    How many should you keep?

    No ratio given; provide spare empty shells

    One US gallon is 3.785 litres and one UK gallon is 4.546 litres, so a "per gallon" rule depends on whose gallon it means.

    What can go wrong?

    Kills snails and other hermits to take their shells

    Which tankmates are risky?

    Fish

    Fish that may eat or harass it.

    None of the fish in this guide is known to eat or harass it.

    Other invertebrates

    Invertebrates it may harm, or that may harm it.

    Take care (7)

    • Trochus snailBlue leg hermit crabs kill snails to take their shells; give spare empty shells.
    • Turbo snailBlue leg hermit crabs kill snails to take their shells; give spare empty shells.
    • Astraea (Astrea) snailBlue leg hermit crabs kill snails to take their shells; give spare empty shells.
    • Cerith snailBlue leg hermit crabs kill snails to take their shells; give spare empty shells.
    • Nassarius snailBlue leg hermit crabs kill snails to take their shells; give spare empty shells.
    • Nerite snailBlue leg hermit crabs kill snails to take their shells; give spare empty shells.
    • Fighting conchBlue leg hermit crabs kill snails to take their shells; give spare empty shells.

    These checks follow the reasons fish and invertebrates clash: same species or genus, similar shape, mouth size, temperament, food, burrows, tank size and the order they are added. Individual animals differ; every source agrees on that.

    Sources

    1. Practical Fishkeeping (UK), essential cleaners for the reef tank (date not shown)Read 21 October 2026, read in full.
    2. Reef Central CUC advice (hermits, emerald crabs)Read 21 October 2026, search summary only.

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    Scarlet reef hermit

    Paguristes cadenati

    Care
    Beginner
    Group
    Hermit crab
    Corals
    Reef safe

    Photo Andreas März, CC BY 2.0

    No licensed photo yet

    Large hermits

    Dardanus, Aniculus, Trizopagurus spp.

    Not for beginners

    Care
    Intermediate
    Group
    Hermit crab
    Corals
    Not reef safe