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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

Pom pom crabs are small, peaceful crabs named for the furry tufts on their claws. They stay mostly in the water and can be kept in a small group, unlike most crabs, so a trio or more gets along in one tank. They are busy scavengers that pick at algae, biofilm, and leftover food. Provide a tight lid and a spot or two of wood or rock near the surface, since they may climb out, and keep copper out of the tank because it is toxic to crustaceans. Feed sinking foods, algae wafers, and bits of vegetable. A tank of 20 liters or more suits a small group.

In the wild

In the wild these crabs live in fast lower-river and coastal streams across South and Southeast Asia, where fresh water runs down toward the sea. They are kept in freshwater aquariums and do well there, though the water should stay hard and well-mineralized, from about 22 to 28 c with a pH from 6.5 to 7.5. Give them a sandy bed, rocks, and driftwood to climb, some gentle flow, and a low water level under a secure lid. Clean, oxygen-rich water keeps them active and molting well.

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, closer to 4 cm counting the legs, and mature males grow the dense claw hairs that give the crab its name. Crabs molt to grow and shelter while the new shell hardens. Breeding is rated hard because the larvae need brackish or salt water to develop and cannot survive in fresh water, so there are no reliable reports of it breeding in a freshwater tank.

Did you know

The tufts are more than decoration. The crab uses its bristly claws to scrape and gather biofilm and fine food from surfaces and the current, then combs the bristles clean with its mouthparts.

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.

How big does a Pom pom crab get?

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

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