TankBud

Red claw crab

Parasesarma bidens

BrackishCrab

Red claw crab (Parasesarma bidens)
RockStarRei · CC BY-SA 3.0

Care at a glance

Temperature
72–82°F
22–28°C
pH
7.5–8.5
Adult size
2 in
5 cm
Minimum tank
10 gal
38 L
Temperament
Aggressive
Social behavior
Solitary
Own kind
One male per tank
Tankmates
With caution
Swim level
Bottom
Difficulty
Medium
Breeding
Hard
Rarity
Very common
Family
Sesarmidae
Origin
Indo-Pacific coastal mangroves and estuaries

Overview

The red claw crab is an aggressive, semi-terrestrial crab for a slightly brackish paludarium. It is a step up from the easiest crabs to keep.

Did you know

Red claw crabs breathe air as readily as water, and they will drown if they cannot climb out. That is why the land area matters as much as the pool.

Caring for the red claw crab

Set up a paludarium of at least 10 gal (38 L), with shallow brackish water plus land or perches above the surface. Keep the water low, so the crabs can climb out. Fit a tight lid, because red claw crabs are determined escape artists. They climb along silicone seams and cords, and a gap in the lid usually means a crab somewhere on your floor.

Keep the water slightly brackish, with marine salt at a specific gravity around 1.005. Hold it at 72 to 82°F (22 to 28°C) and on the alkaline side, at a pH of 7.5 to 8.5. Pure fresh water shortens their life. Feed a mixed diet of sinking pellets, blanched vegetables, frozen foods and the occasional bit of protein.

Keep one crab on its own, or one male with several females. Red claw crabs are aggressive and territorial bottom dwellers, especially the males. They will turn cannibalistic, so do not crowd them. Skip fish and shrimp as tank mates, since the crab will go after anything it can catch.

The red claw crab is a marine breeder whose larvae need full ocean salinity to develop. That makes breeding it in a home tank hard.

Good to know

The red claw crab, Parasesarma bidens, is a small crab in the family Sesarmidae. Most red claw crabs in the trade are wild caught from coastal habitats rather than captive bred. With good care they live a few years.

In the wild

Red claw crabs come from coastal mangroves and estuaries across the Indo-Pacific. They spend as much time out of the water as in it. They are brackish, semi-terrestrial animals rather than freshwater ones, even though shops often mislabel them.

Common questions

What size tank does a red claw crab need?

A red claw crab needs at least 10 gal (38 L). It spends most of its time in the bottom.

What temperature and pH does a red claw crab need?

A red claw crab is comfortable at 72–82°F (22–28°C) with a pH of 7.5–8.5.

What does a red claw crab eat?

A red claw crab eats a mixed diet of sinking pellets, blanched vegetables, frozen foods and the occasional bit of protein.

How big does a red claw crab get?

An adult red claw crab reaches about 2 in (5 cm).

How does a red claw crab breed?

A red claw crab is a marine breeder, and its larvae need full ocean salinity to develop. That makes breeding it in a home tank hard.

Related species