TankBud

Scarlet reef hermit crab

Paguristes cadenati

Also known as Red Reef Hermit Crab, Red Legged Hermit Crab, Scarlet Leg Hermit Crab, Gold Faced Hermit Crab

SaltwaterCrab

Scarlet reef hermit crab (Paguristes cadenati)
Andreas März from Darmstadt, Germany · CC BY 2.0

Care at a glance

Temperature
72–79°F
22–26°C
pH
8.1–8.4
Adult size
1.6 in
4 cm
Minimum tank
11 gal
40 L
Temperament
Peaceful
Social behavior
Social
Swim level
Bottom
Difficulty
Beginner
Breeding
No record
Rarity
Very common
Reef safe
Reef safe
Family
Diogenidae
Origin
Western Atlantic, from south Florida and the Gulf of Mexico through the Bahamas and the Caribbean Sea to the Lesser Antilles

Overview

The scarlet reef hermit crab is a tireless scavenger and one of the most commonly stocked cleanup-crew animals in the hobby. It is an easy pick for a first reef tank.

Did you know

Before moving in, a scarlet reef hermit crab sizes up a new shell by spinning it in its claws and probing the inside opening. If the fit is right, it can swap homes in just a few seconds.

Caring for the scarlet reef hermit crab

Keep the scarlet reef hermit crab in an established reef of at least 11 gal (40 L), with algae growth to pick at. Give it open rock and glass to work over. It spends most of the day out foraging rather than hiding.

Hold the water at 72 to 79°F (22 to 26°C) with a pH of 8.1 to 8.4. It eats algae, detritus and leftover food, and it is particularly fond of hair, filamentous and slime algae along with cyanobacteria. It will also pick at fish food and prepared invertebrate diets.

It moves up to a roomier shell each time it molts and outgrows the old one. Keep a stock of assorted empty shells in the tank at all times. Without spares, it may attack and evict a living snail to get a new shell. Otherwise it is peaceful toward fish, corals and most tankmates.

Good to know

Paguristes cadenati is a small hermit crab in the family Diogenidae. Its bright scarlet-red legs, deep red antennae and yellow to yellow-green eyestalks set it apart from other reef hermits. Its left claw runs slightly larger than the right. Like other hermits, it has a soft, unarmored abdomen protected by a scavenged gastropod shell. In the wild, that is most often a Cerithium or Vasum shell.

In the wild

The scarlet reef hermit crab lives on Caribbean and western Atlantic reefs and rubble, from the shallows down past 50 meters. It ranges from south Florida and the Gulf of Mexico through the Bahamas and the Caribbean Sea to the Lesser Antilles. It grazes rock and rubble for algae and detritus, tucked into a borrowed shell for protection.

Common questions

What size tank does a scarlet reef hermit crab need?

A scarlet reef hermit crab needs at least 11 gal (40 L). It spends most of its time in the bottom.

What temperature and pH does a scarlet reef hermit crab need?

A scarlet reef hermit crab is comfortable at 72–79°F (22–26°C) with a pH of 8.1–8.4.

What does a scarlet reef hermit crab eat?

A scarlet reef hermit crab eats algae, detritus and leftover food, especially hair, filamentous and slime algae and cyanobacteria. It also picks at fish food and prepared invertebrate diets.

How big does a scarlet reef hermit crab get?

An adult scarlet reef hermit crab reaches about 1.6 in (4 cm).

Related species