White-spotted hermit crab (Dardanus megistos) care guide

Group
Other invertebrates
Other names
Spotted hermit crab, Red hermit crab, Giant red hermit, Dardanus spinimanus, Pagurus punctulatus
Family
Diogenidae
Origin
Indo-Pacific, from East Africa to the South China Sea, Australia and Hawaii, on reefs, lagoons, rocky platforms and sand and seagrass, down to 50 m
Water
saltwater
Maximum size
20 cm
Temperature
23–27°C
pH
8.1–8.4
Hardness
dKH 8–12, SG 1.023–1.025
Minimum tank
400 litres
Care level
intermediate
Temperament
aggressive
Reef safe
no
Lifespan
up to 30 years

Care

The white-spotted hermit crab is a large Indo-Pacific hermit crab, with a body up to about 20 cm long. It is bright red, covered in white black-ringed spots and long, coarse dark red hairs. The left claw is larger than the right. It lives in large sea snail shells and can live for up to 30 years. Set-up: it needs a large tank of 400 litres or more with sand, sturdy rockwork and a supply of larger empty snail shells to move into as it grows. Water figures here are general reef guidance rather than from a source. Aim for 23–27 °C, pH 8.1–8.4, dKH 8–12 and SG 1.023–1.025. Behaviour: it is an opportunistic predator, eating worms and molluscs and reported to eat sea cucumbers. It will catch and eat snails, crabs, shrimp, clams and sleeping fish, and it moves rock and corals. It is not part of a reef clean-up crew; it suits large fish-only or predator tanks. Shells: hermits need spare shells of the right size, or they may kill snails to take theirs or fight other hermits. Provide shells slightly larger than the current one. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most other invertebrates. Never treat a tank holding them with copper, check the label of any fertiliser or medicine, and keep nets and buckets used for copper-treated tanks separate. Sources: Wikipedia (en.wikipedia.org/wiki/Dardanusmegistos). Checked October 2026.

Diet

An opportunistic omnivore that mainly eats small invertebrates such as worms and molluscs. In aquariums feed chopped fish, shrimp, mussel and squid, sinking pellets and some algae.

Breeding

Sexes are separate, and pairs perform a courtship ritual before mating. Females carry eggs on the abdomen. The larvae are planktonic and are not raised in home tanks.

Compatibility and tank mates

Not reef safe. It will eat snails, small crabs, shrimp, clams, starfish and small or sleeping fish, and damages corals and rockwork by bulldozing. Keep with large, robust fish such as large angelfish, tangs and puffers, though puffers and triggers may attack it. Do not mix with small hermits or clean-up crews.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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