Hermit crab

Scarlet reef hermit

Paguristes cadenati

Also sold as Red leg hermit

Group: Hermit crab
Care level: Beginner
With corals: Reef safe

What does the scarlet reef hermit do in a reef tank?

Algae (including hair algae and cyanobacteria), detritus, leftovers

With corals: Yes (described as peaceful)

How many should you keep?

1 per 25 L (5.5 US gal)

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?

Spare shells still advised

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.

None known.

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

Practical Fishkeeping (UK), essential cleaners for the reef tank (date not shown)Read 21 October 2026, read in full.

Last checked 21 October 2026. How we check

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