Red Claw Crab 101: Care, Tank Setup, Diet & More

Red Claw Crabs are a fascinating and exciting brackish species to own. With their beautiful colors and high activity level, these critters will certainly keep you occupied.

But like all brackish creatures with aggressive tendencies, you need to know what you’re doing if you want to own one. That’s why we put together this guide.

This resource has everything you need to know about Red Claw Crab care. It includes info about their ideal tank setup, diet, tank mates, average lifespan, and more!

Species Summary

Red Claw Crabs (scientifically known as Perisesarma Bidens) are unique little creatures that you can keep in your aquarium. While they may be shy and defensive, these crabs are full of character.

Originally, these crabs hail from bodies of water throughout Asia. They can be found in shallow rivers and estuaries that meet with the sea. Thus, their natural habitat is typically brackish.

Contrary to popular belief, Red Claw Crabs are not freshwater crustaceans. While they can survive in a purely freshwater tank, but they will not reach their full life expectancy unless they have some brackish water to live in.

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Despite the ever-growing popularity of Red Claw Crabs, there are still a lot of misconceptions about these invertebrates. They are a unique creature to care for with some distinct needs that you have to address.


In captivity, the average Red Claw Crab is between 2 and 2.5 years.

However, this is only possible if you’re providing them with the very best environment! Like all aquatic animals, these crabs are sensitive to water conditions.

Red Claw Crabs are special critters that you need to be extra careful with. They’re often advertised as freshwater aquatic crabs. That’s simply not true. These crabs need both air and brackish water to truly thrive.

When kept in freshwater Red Claw Crabs have much shorter lifespans. Many will only last a few months. The same goes for crabs that are unable to access fresh air.

Even if you do things right and provide brackish water, you’ll need to stay on top of water conditions to keep your crabs healthy (more on that later). Inferior conditions can lead to undue stress, disease, and a shorter life expectancy.


Red Claw Crabs are stunning crustacean with some standout features. With most specimen, the main body is relatively neutral. It’s usually brown and accompanied by spots for easy camouflage.

You might see some large patches of dark black on top of their heads as well. It’s usually found in the center of their carapace. On the two corners of their head, these crabs have bulging, antennae-like eyes.

Perisesarma bidens looking for food in an aquarium

In total, the Red Claw Crab has 10 legs. The first eight are built for walking around sandy environments. They’re pointed and usually take on a similar color pattern to the rest of the body.

The most identifying feature of these crabs is their claws! As you might have guessed, their claws are bright red in color. The tips may be colored orange or yellow. Brightness and color can vary slightly from crab to crab, but all specimen have vivid red claws.

There are some subtle differences between male and female crabs. Males tend to have meatier claws. They’re usually also a bit more vivid in terms of coloration.

Like other crab species, you can also easily distinguish between male and female specimen by taking a look at the underside of their bodies. The crabs have a small flat flap. For males, the flap is triangular or pointy. With females, it’s broad and round.

Average Size

The typical size of an adult Red Claw Crab is about 4 inches (this is measured in leg span).

Author Note: However, their carapace is much smaller. The main body of the crab is usually only about 2 to 2.5 inches wide.

Red Claw Crab Care

Red Claw Crab care requires you to be aware of the unique conditions that these animals need. You can’t just pop them in a freshwater tank and call it day! Their habitats should be carefully crafted and heavily monitored.

The good news is that creating their environment isn’t too difficult if you know what to do. It can be a fun process that results in a beautiful aquarium setup.

Tank Size

We recommend a tank size of at least 10 gallons if you plan on keeping Red Claw Crabs. 

While some aquarists haven’t had any problems keeping these crabs in tanks as small as 5 gallons, a bit of extra space makes a big difference. While they might be small, they need plenty of space to explore and claim territory.

A 10-gallon tank should be suitable for a single male and a couple of females. As always, go with a larger tank if possible. The more space these crabs have the better!

This is because they’re highly territorial and can exhibit signs of aggression. We’ll get into that a bit later.

Author Note: If you’re able to invest in a paludarium, that’s an even better choice. A paludarium is a unique tank that’s designed to accommodate both underwater and land environments. If you go with one of these tanks, choose a model that’s about 60 centimeters, or 24 inches, wide.

Water Parameters

Providing the right water parameters is probably the most important part of Red Claw Crab care.

If you want to keep this species happy and healthy you’ll need to replicate their natural environment in the wild.

Normally they can be found in waters all throughout Asia. Typically, these bodies of water are rather shallow.

They are frequently found in mangrove swamps around the coasts. This means the water in your tank should be hard, slightly alkaline, and brackish.

The brackish element is the most important piece of the puzzle. In order to provide this, you’ll need to add some marine salt to the water to give is some slight salinity. To give you a point of reference, it’s only about a sixth of the saltiness as pure ocean water.

Here are some parameters to follow closely:

  • Water temperature: 70°F to 88°F (your target should be the middle of this range)
  • pH levels: 7.5 to 8.5
  • Water hardness: 8 to 25 dGH
  • Specific gravity: 1.005

Author Note: Since these critters are so particular when it comes to water conditions, you should be performing regular tests to ensure that the parameters are where they need to be. Get a reliable testing kit that will give you readings you can trust.

Tank Setup & Decorations

Putting together the perfect tank setup for Red Claw Crabs is quite fun and unique! As we said earlier, these crustaceans need land and water to stay healthy.

Ideally, you should keep the water to land ratio around 3 to 1. That means the habitat should be primarily water with some chunks of land for the crab to relax on.

Start by applying some sand substrate. Sand is best for Red Claw Crabs because they like to scavenge, dig, and burrow. It’s a safe and easy material for them to maneuver on.

You can build a landmass with the sand if you’re using a standard aquarium. Some paludariums have built-in shelves to make it easier to create sandy landmasses. Alternatively, you could always use floating perches.

One Red Claw Crab sitting on top of a plant

In the water, you should implement several natural decorations.

Driftwood and rocks are good options. The crabs will use them whenever they feel threatened or scared. They’re especially important when the crab molts.

Plants are good too, but Red Claw Crabs are notorious for shredding and uprooting plant leaves. Their claws are made for slicing, so they have no problem ruining your plants!

They’re particularly fond of brackish Java Ferns. To overcome destructive behavior, you can utilize silk plants instead of live ones.

As always, a strong filtration system is required. Go with a marine filtration system if possible. They can cycle the water efficiently without affecting the salinity levels too much. Either way, we always recommend performing a 10 percent water change every week to keep levels in good shape.

On top of the tank, make sure that you have a strong lid. Red Claw Crabs are cunning escape artists. They have been known to crawl up inlet tubes and escape through any little gap they can find.

Unfortunately, these crabs don’t survive very long if they don’t have access to water. They’ll quickly dehydrate out of the tank, so it’s important to make sure that they can’t get out!

Common Possible Diseases

One great characteristic of Red Claw Crabs is that they’re very resilient against disease. These invertebrates have been known to feast on sick and diseased fish without experiencing any problems whatsoever.

However, they can experience bacterial and fungal infections. Parasitic infestations are known to occur as well. Fortunately, all of those issues are very rare.

Overcrowding and stress have been known to increase the chances of disease in Red Claw Crabs, so make sure to keep these creatures comfortable. Regular water changes and heavy monitoring of water conditions can help you avoid illness as well.

Food & Diet

Red Claw Crabs can be quite predatory. However, they’re omnivores that will accept anything you give them. In most cases, predatory behavior is actually more about territorial disputes than food.

To keep your crabs healthy you can feed them a varied diet of protein and vegetables.

They love snacking on bloodworms, brine shrimp, and pieces of uncooked fish or shrimp. As for vegetables, you can provide blacked spinach, peas, or other leafy greens.

In the wild, they feast on mangrove leaves pretty frequently. As a result, you’ll often find them chowing down on any plant leaves they can get their claws on in the tank.

Standard commercial foods work well, too. The crabs do fine with algae pellets and sinking fish food. In our opinion, they seem to prefer the other foods though.

Behavior & Temperament

Red Claw Crabs can be a joy to watch. That is, however, if they let you watch them!

These crabs are known to be quite skittish and tend to do most of their exploring at night. During the day this species will spend a lot of time hiding.

Over time, many owners have reported that these critters will stop hiding. Once they get comfortable with the environment and your presence, they should become more active. You’ll be able to watch them scavenge for food and burrow around the substrate.

But be careful, these crabs can be quite aggressive.

They are territorial creatures that will fight to protect their space. If another crab or fish encroaches on that territory, be prepared for some feisty behavior!!

If they’re upset or frightened they’ll raise their claws. Sometimes they’ll retreat and hide, and other times they’ll attack. They have been known to kill other fish and animals, so be careful about what you put in the tank.

Author Note: Another thing to be wary of is the molting process. Like other invertebrates, Red Claw Crabs will get rid of their shells as they grow.

During this time, they are very vulnerable to attack. Provide plenty of hiding spots so that they can feel safe as their new shells harden!

Red Claw Crab Tank Mates

First of all, let’s get one thing straight:

Red Claw Crabs are best kept in species-specific tanks. There’s a couple of reasons for this.

First, they’re incredibly territorial and have been known to fight. Secondly, their brackish nature makes it difficult to find compatible tank mates.

However, some aquarists have been able to keep peaceful fish as Red Claw Crab tank mates as well. If you go this route, you’ll need to choose peaceful, fast-swimming fish that stick to the top of the aquarium.

Fish like Flagfish, Mollies, and larger Gobies (don’t pair them with the Bumblebee Goby) have been known to do well.

Just keep in mind that your tank needs room for dry land. As a result, the underwater portion will be much smaller.

Your best bet would be to keep only a few Red Claw Crabs together. The best scenario is a single male with one or two females. Mulitple males should not be kept in the same tank together.

They will be aggressive and fight one another until there’s only one left! This may also happen with females, but it’s not as widespread.

To avoid aggressive behavior as much as possible, provide the largest tank possible and utilize as many hiding spots as you can. Every crab should have their own space where they can be alone.


Breeding Red Claw Crabs in captivity is nearly impossible. Some aquarists have seen the creatures spawn in tanks. However, the eggs rarely ever hatch. Even those that do tend to die off quickly.

These crabs begin their lives as larvae, so they are very vulnerable to attacks. The crabs don’t exhibit any parental behavior whatsoever. In most cases, the adults will feast on the larvae.

With the closed nature of an aquarium, the chances of survival for Red Claw Crab babies are next to zero.            

Are You Still Interested In This Species?

Now that you have a full understanding of what proper Red Claw Crab care entails, it’s time to decide if this species is right for you.

Like all brackish creatures, these crabs require a little bit of extra effort and knowledge if you want them to thrive. While some aquarists view this as a hassle they want to avoid, others find it an appealing challenge.

If you’re in the latter category, we definitely recommend giving these animals a chance. Not only are they a ton of fun, but they’re extremely rewarding to keep!

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