Red Claws Crab Aquarium Care Guide

Red Claw Crabs are fascinating creatures, but keeping them in an aquarium can be challenging. Their specific habitat requirements mean they need diligent care to thrive. Below, we’ll give you some of the essential information and advice you need to keep red claw crabs successfully.

Key Takeaways

  • Red claw crabs, Perisesarma bidens, belong to the family Sesarmidae family and reside in mangrove habitats across the Indo-Pacific region.
  • They have adapted to living in brackish water and require a mix of saltwater and freshwater.
  • Red claw crabs have striking carapaces and a total of 10 legs, with their last two being the signature red claws that give them their name.
  • They require a tank size of at least 10 gallons for a single male and a couple of females and need a semi-aquatic tank environment with perches above the waterline to mimic their natural habitat.
  • They need a pH between 7.5-8.5, water hardness of 8-25 dGH, a good filtration system, and regular water changes

Red Claw Crabs Taxonomy

Red Claw Crabs, scientifically known as Perisesarma bidens, are one of numerous species in the genus. P. bidens is easily distinguishable by its vibrant color, which varies from red to orange and purple hues.

Their scientific classification is as follows:

  • Kingdom: Animalia
  • Phylum: Arthropoda
  • Subphylum: Crustacea
  • Class: Malacostraca
  • Order: Decapoda
  • Family: Sesarmidae
  • Genus: Perisesarma
  • Species: P. bidens
by Marrabbio2 (CC BY-SA 3.0)

Red Claw Crab Basics


Red claw crabs typically displays patterns of brown, yellow, and orange. They have a total of 10 legs, of which two are their signature red claws.

Red Claw Crabs exhibit sexual dimorphism, meaning that males and females have distinct physical differences. Males possess larger claws and slimmer abdomens, while females have smaller claws and broader, rounder abdomens. 


When properly cared for in an aquarium, red claw crabs have a lifespan of two to three years. 


These small crabs reach an average leg span of 2 to 4 inches (5-10 cm). Males have larger claws compared to the females, which can be used to distinguish between the two sexes.

by Björn König (CC BY-SA 3.0)

Natural Habitat

Red claw crabs originate from Asia, where they inhabit brackish water in mangrove swamps and estuaries. Their natural habitat contains plenty of vegetation and hiding places, and always allows them to move between dry land and water.

Mangrove Swamps withTank Setup And Maintenance

Aquarium or Paludarium

Red Claw Crabs can be kept in either a paludarium or an aquarium with a low water level and decor extending above the water line. These crabs are not fully aquatic and absolutely must have an area where they can emerge from the water.

Their preferred habitat is A mix of land and water, with a land to water ratio of 3 to 1.

Aquarium Size

A single male and a few female red claw crabs require a tank size of 10 gallons or more. A bigger tank is always better, and will allow them the space they need to move about and live happily.

Substrate and Decoration

A sandy substrate is the most suitable choice for red claw crabs, as it allows them to burrow easily. These crabs are fond of burrowing, and will appreciate a nice, deep layer of sand. In some cases, certain types of sand can also help boost their Calcium intake.

You should also add decorations like rocks, driftwood, and caves for them to climb over and hide under.

by Marrabbio2 (CC BY-SA 3.0)

Water Conditions

These crabs need brackish water with a mix of marine salt and freshwater. Ensure that the water pH is between 7.5-8.5, and maintain a level of water hardness suitable for their habitat. 

Brackish water can be maintained in aquariums by mixing one to two tablespoons of marine salt per gallon of fresh water. This creates a palatable mix for the red claw crab, closely resembling their natural habitat.

Filtration System

A good filtration system is crucial to maintain a clean and healthy environment for your red claw crabs. Choose a reliable filter that can handle the tank size and the waste produced by the crabs. A canister filter or other strong mechanical filter is a great choice.

Heater and Temperature

Red claw crabs thrive in water temperatures between 72-82°F (22-28°C). Use a dependable aquarium heater to maintain the desired temperature consistently.

Tank mates

Red Claw Crabs are territorial and aggressive creatures that can be challenging to keep with other species. Further complicating the matter is the fact that they require relatively shallow brackish water. Many aquarists believe that it’s better to keep them by themselves. If you were to try keeping fish in their paludarium, you might want to consider something unobtrusive like the bumblebee goby.

Feeding And Diet

Red Claw Crabs are scavenging omnivores, meaning they consume both plant and animal matter. In captivity, it is essential to offer a varied diet to ensure optimal health.

In terms of live foods, they are particularly fond of:

  • Bloodworms
  • Brine shrimp
  • Uncooked fish
  • Uncooked shrimp 

You can also add vegetables to their diet, including the following:

  • Blanched spinach
  • Peas
  • Leafy greens 

In the wild, mangrove leaves are a common part of their diet.

When feeding Red Claw Crabs, consider using a combination of store-bought flake or pellet foods, algae wafers, and the previously mentioned live foods. Rotating their food sources helps mimic their natural feeding habits and keeps them healthy and active.

Lastly, monitor the amount of food given, as overfeeding can lead to poor water quality and other health issues for the crabs. Aim to feed them no more than they can consume in 15 minutes, twice a day.

Behavior And Characteristics

Territorial and Aggressive Tendencies

Red claw crabs exhibit territorial and aggressive behavior. When encountering another crab or tank mate, they often raise their claws, signaling a defensive stance that can quickly become offensive.

A red claw crab may attack a smaller tank mate, especially if the crab feels threatened. Providing ample hiding spots and enough space for each crab can help reduce the likelihood of aggressive encounters.

Molting Process

Molting is an essential process for red claw crabs, allowing them to grow by shedding their old exoskeleton. This process can cause stress as it leaves the crab vulnerable to injuries or attacks. Providing a stress-free environment and varied diet during this time is crucial for the crab’s health and wellbeing. The crab will go into hiding for a few days as it undergoes this process, as it will be very vulnerable and susceptible to attacks from tank mates.

Escaping their tanks

Red Claw Crabs, can be quite resourceful when it comes to escaping their tanks. Keep their aquarium secure to prevent any unintentional adventures, and ensure that there are no holes the crabs can escape through.

Breeding And Reproduction

Despite being territorial and aggressive, Red Claw Crabs can still reproduce in captivity. To optimize breeding conditions, create an environment miming their natural habitat, such as providing mangrove roots and a brackish water system. This encourages breeding and ensures a higher likelihood of success with reproduction.

Female Red Claw Crabs carry their eggs under their tails. When they’re ready to spawn, you’ll notice the eggs change color from reddish to gray over a period of approximately three weeks. During this time, it’s essential to provide a safe environment in which the eggs can hatch uninterrupted.

When breeding Red Claw Crabs, monitor the aquarium closely to avoid potential problems, like cannibalism among the newborns. After hatching, the baby crabs will molt multiple times before reaching adulthood. Provide them with a nutritious and well-balanced diet to support their growth and development.

Shell Rot

Several diseases can affect Red Claw Crabs, but shell rot is the common. It’s usually caused by a bacterial infection, and symptoms often include discolored and flaking shells. If caught early, this illness can be treated by adjusting water quality or administering medication as needed.

They have special plates that help retain moisture in their gills, allowing them to breathe even in dry air.


Red Claw Crabs make unique and exciting pets as long as you meet their specific and unusual care needs. If you follow the instructions given here, these animals will give you many hours of enjoyment and relaxation.

If you are interested in crabs you might find the following care guides useful:

Panther crab – the ultimate care guide

Vampire crab care guide

Thai Micro Crab care guide

Fiddler Crabs care guide

About the author

Hi, I am Alex.
My passion is aquariums. I am especially drawn to betta fish. I love experimenting, learning, researching, and writing about them.

You can find the articles I wrote here

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