TankBud

Brackish hermit crab

Clibanarius longitarsus

Also known as Javanese freshwater hermit crab, Freshwater hermit crab, Blue-striped hermit crab, Mangrove hermit crab

BrackishCrab

Brackish hermit crab (Clibanarius longitarsus)

Care at a glance

Temperature
75–84°F
24–29°C
pH
7.6–8.4
Adult size
2 in
5 cm
Minimum tank
16 gal
60 L
Temperament
Mostly peaceful
Social behavior
Social
Tankmates
With caution
Swim level
Bottom
Diet
Omnivore
Difficulty
Medium
Breeding
No record
Rarity
Rare
Family
Diogenidae
Origin
Indo-West Pacific mangroves and estuaries, Red Sea to Japan and Australia

Overview

The brackish hermit crab is a busy scavenger that helps clean a brackish tank of gobies or mollies. It is best with a little experience.

Did you know

Only one true freshwater hermit crab exists in the world, Clibanarius fonticola, from a single spring-fed pool on Espiritu Santo, Vanuatu. Every hermit crab sold as a freshwater pet anywhere else is a brackish or marine animal. The brackish hermit crab is the species most often behind that label.

Caring for the brackish hermit crab

Give a few brackish hermit crabs a tank of at least 16 gal (60 L), with a sand bed, roots and a tight lid. Most of all, keep a pile of empty snail shells in a range of sizes on the bottom. A hermit crab with no bigger shell to move into is stuck.

It will hang on in fresh water for a few months, but it is a brackish animal and slowly fails without salt. Mix marine salt to a specific gravity of 1.005 to 1.015. Keep the water at 75 to 84°F (24 to 29°C) with a pH of 7.6 to 8.4.

It works the sand for algae, detritus and leftovers all day. Feed algae wafers, sinking pellets and frozen foods on top of what it finds, and let some algae grow.

The brackish hermit crab is mostly peaceful, but a hungry one grabs small fish. Any hermit will kill a snail for its shell, so skip snails you care about. It is fine alone or in a group, and a group gets along when there are enough shells, though males squabble over the best ones. Its larvae develop in the sea, and there is no record of it breeding in captivity.

Good to know

Clibanarius longitarsus is a hermit crab in the family Diogenidae, described by De Haan in 1849. Its two pincers are about equal in size. The body is pale, the pincers olive brown with blue green bumps, and the legs carry two dark stripes. Those stripes are why it is called the blue-striped hermit crab in Singapore. Wild crabs on Singapore shores are only 1 to 2 cm long.

In the wild

The brackish hermit crab lives in mangroves, on mudflats and sandy shores, and in seagrass across the Indo-West Pacific. It also enters the lower reaches of rivers, in water that swings from nearly fresh to full sea with the tide. Its range runs from the Red Sea and East Africa to Japan, the Philippines, Indonesia and Australia.

Common questions

What size tank does a brackish hermit crab need?

A brackish hermit crab needs at least 16 gal (60 L). It spends most of its time in the bottom.

What temperature and pH does a brackish hermit crab need?

A brackish hermit crab is comfortable at 75–84°F (24–29°C) with a pH of 7.6–8.4.

What does a brackish hermit crab eat?

A brackish hermit crab scavenges algae, detritus and leftovers from the sand. Feed it algae wafers, sinking pellets and frozen foods on top of that, and let some algae grow. A hungry one will also grab small fish.

How big does a brackish hermit crab get?

An adult brackish hermit crab reaches about 2 in (5 cm).

How does a brackish hermit crab breed?

A brackish hermit crab's larvae develop in the sea. There is no record of it breeding in captivity.

Related species