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Pom pom crab

Ptychognathus barbatus

FreshwaterCrab

Pom pom crab (Ptychognathus barbatus)

Care at a glance

Temperature
72–82°F
22–28°C
pH
6.5–7.5
Adult size
1.6 in
4 cm
Minimum tank
5 gal
20 L
Temperament
Peaceful
Social behavior
Social
Swim level
Bottom
Difficulty
Easy
Breeding
Hard
Rarity
Rare
Family
Varunidae
Origin
Southeast Asia, South Asia

Overview

The pom pom crab is a small, peaceful crab that stays mostly in the water. It is easy to keep in a freshwater tank.

Did you know

The pom pom crab's tufts are more than decoration. It uses its bristly claws to scrape and gather biofilm and fine food from surfaces and the current. Then it combs the bristles clean with its mouthparts.

Caring for the pom pom crab

Pom pom crabs can be kept in a small group, unlike most crabs, and a trio or more gets along in one tank. Give them at least 5 gal (20 L), with a sandy bed, rocks and driftwood to climb. They may climb out, so fit a tight lid and keep the water level low. Add a spot or two of wood or rock near the surface.

They do well in freshwater aquariums, though the water should stay hard and well mineralized. Keep it at 72 to 82°F (22 to 28°C) with a pH of 6.5 to 7.5 and some gentle flow. Keep copper out of the tank, because it is toxic to crustaceans.

Pom pom crabs are busy scavengers that pick at algae, biofilm and leftover food. Feed sinking foods, algae wafers and bits of vegetable. They molt to grow and shelter while the new shell hardens. Clean, oxygen-rich water keeps them active and molting well.

Mature males grow the dense claw hairs that give the crab its name. Breeding is rated hard, because the larvae need brackish or salt water to develop and cannot survive in fresh water. There are no reliable reports of it breeding in a freshwater tank.

Good to know

Ptychognathus barbatus is a small crab in the family Varunidae, the group of shore and estuary crabs. Its shell is only about 2 to 2.5 cm wide, and its adult size includes the legs.

In the wild

Pom pom crabs live in fast lower-river and coastal streams across South and Southeast Asia. In these streams, fresh water runs down toward the sea.

Common questions

What size tank does a pom pom crab need?

A pom pom crab needs at least 5 gal (20 L). It spends most of its time in the bottom.

What temperature and pH does a pom pom crab need?

A pom pom crab is comfortable at 72–82°F (22–28°C) with a pH of 6.5–7.5.

What does a pom pom crab eat?

A pom pom crab is a busy scavenger that picks at algae, biofilm and leftover food. Feed it sinking foods, algae wafers and bits of vegetable.

How big does a pom pom crab get?

An adult pom pom crab reaches about 1.6 in (4 cm).

How can you tell a male pom pom crab from a female?

Males grow the dense claw hairs that give the crab its name once they mature.

How does a pom pom crab breed?

A pom pom crab's larvae need brackish or salt water to develop and cannot survive in fresh water. There are no reliable reports of it breeding in a freshwater tank, and breeding is rated hard.

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