Red Claw Crab: All the Information You Need

Have you ever thought to buy some freshwater crabs for your tank? Well, that’s great because today we are going to talk about a crab species, which is red claw crab. Maybe after reading this article you will immediately head to the fish store and get yourself some red claw crabs for your aquarium. We will try to cover all the spheres referring to these species. So continue reading for all the information about red claw crabs.

red claw crab

Red Claw Crabs [Quick Overview]

Red Claw Crabs need both saltwater and air to survive. They have a lifespan of around 2-2.5 years. They eat spinach, peas, bloodworms, and raw shrimp. They are sensitive and require top-of-the-line care to stay healthy.

General information

Red claw crab is also known as Perisesarma bidens, mini crab, Sesarma bidens, or Sesarma moeschi. These species are often mistaken for freshwater crabs but they feel perfect in brackish water. These species can naturally be found in Asia. They live in tropical temperature areas with shallow water and sandy ground. Red claw crabs can grow a maximum of up to 10 cm and are relatively smaller than most other aquarium crab species. That is why they are also known as mini crabs. You can differentiate male crabs from females by the red claws which are larger in males and the underside of the male shell is pointier while in females’ rounder. Usually, these crabs have a lifespan of around 2 years.

Red Claw Crab Appearance

Most Red Claw Crabs have a comparatively pale main body, distinguishing them from other crabs. It’s usually brown with dots for a stylish look. Some species have dark black spots on the tops of their heads that are usually enormous, with protruding feelers on the corners that resemble eyes. The primary eight legs of a Red Claw Crab are designed for walking, pointed, and camouflaged in colors that match the rest of the crab.

Claws of Red Crabs are known for their brilliant red talons with yellow or orange tips, which vary in colors and brightness depending on the type. Male crabs have fleshier claws and are a brighter hue than female crabs. The little flap underneath them clearly shows the underside of their bodies. Male crabs have a pointy, trilateral flap, while female crabs have a circular, wide fold.

Lifespan Of Red Claw Crab

A Red Claw Crab’s lifespan in captivity is usually between 2-2.5 years due to its sensitivity to changes in the water environment. These crabs, sometimes known as freshwater, marine crabs, require both saltwater and air to flourish. However, these crabs have a much shorter lifespan in freshwater, sometimes as little as a few months. Therefore, even under near-ideal water conditions, they demand top-of-the-line care to stay healthy, and anything less will be damaging to their survival.

Red Claw Crab Size

The average size of a red claw crab is measured in its leg span and is about 4”; however, its sheath is much smaller, the crab’s main body is just 2-2.5” wide.

Red Claw Crab Care & Tank Setup

It requires more than simply dumping these unique creatures into a freshwater tank and letting them go. Special adjustments to the red-clawed crab care are required to keep them comfortable. Their surroundings must be meticulously kept and supervised. If you know what you’re doing, creating their habitat isn’t difficult at all. With specific water requirements, it is critical to create a brackish water habitat for red claw crabs, which requires a 1/6th marine salt mix in their tank.

Red claw crabs are omnivorous and born predators. They enjoy feeding on green leaves, spinach, and blanched peas as well. In Addition, thrive on flaked fish, bloodworms, raw shrimps, pellets, and brine shrimps.

Tank Type & Specifications

An average requirement for red claw crabs is a tank capacity of roughly 10 gallons, depending on how many you plan to keep. Although these crabs are modest in size, they require a large amount of room to move and claim as their own.

Optimum Tank Size

A tank with 10 gallons is ideal for female crabs and a single male crab. Alternatively, if a paludarium is available, it is strongly recommended. A paludarium is a unique tank containing land and marine life, and a 60cm/24″ wide paludarium would be ideal for this! 

Because these creatures are naturally destructive, having a specially adorned tank won’t help you much. To aid the crabs throughout the molting season, you can add aquarium shelter and driftwood at random. Artificial plants and saltwater java fern can be used as decorations.

If you plan to have red claw crabs in the same tank, make sure it’s big enough to avoid confrontations, as these crabs are naturally aggressive and loners. Mollies, tetras, guppies, and flag fish are non-aggressive, fast-swimming fish.

Filter Type

A red claw crab tank, like fish habitat, requires effective filtration that is appropriate for the tank size and volume of water in it. Because crabs can readily make their way into an internal filtering system, the flow of water coming in and out must be monitored. An aquatic filtration system aids the water cycle without affecting the saline levels, and it’s essential to change at least 10% of the water each week to keep the tank running smoothly.


Because Red Claw Crabs enjoy digging, burrowing, and scavenging, therefore, sand is the perfect substrate for them. Because sand is easier for crabs to navigate, you can design a unique floating perch or landmass in a regular tank. Crabs prefer to hide beneath or between stones and fissures in the rock. Lightly colored sand can create contrast between the tank floor and the crabs.

Feeding red claw crabs

These crabs love to hunt actively but they are not very strict carnivores. You should feed your red claw crabs with plenty of protein such as bloodworms or uncooked fish in small pieces. The diet of red claw crabs should also include a lot of vegetables, such as spinach, peas, and leafy greens. You can feed your red claw crabs with regular fish food as well, such as commercial crab food and algae pellets.

What tankmates should you get for red claw crabs?

As red claw crabs are territorial it is not recommended to keep many males in one tank as they may start a territorial war and even can kill each other. For instance, in a 60 cm paludarium you can keep one male and up to 3 female crabs. It is way easier to keep red claw crabs in a one species setup, but if you find that your tank is large enough for more species then you can get some tankmates.

But notice that crabs can hurt some fish, especially the slow ones. Tankmates should stand low-end brackish water and should not be bottom dwellers.

Breeding Red Claw Crab

A red claw crab has no chance of surviving in the enclosed confines of an aquarium. The temperature of the water and the length of the day are also important factors in their breeding process, which takes place between September and April. Farmers can extend the breeding season in a controlled environment by changing the temperature to mimic the start of the mating season.

Certain superior grade red claw strains are cultivated in exclusively created tanks to enhance natural mating, which results in good prospects of red claw crabs for sale, which varies by location and farm. Female crabs lay their eggs for 6 to 10 weeks, and the larger the crab, the more eggs she will lay. 

During the mating season, a red claw can produce 3-5 clutches, with most females brooding 300-800 eggs each clutch. The babies look like adult crabs and remain attached to the female crab’s underbelly for several weeks before becoming self-sufficient.

Red Claw Crab Common Diseases & Treatment

A red claw crab is notable for its disease resistance. Typically, it feeds on infected and ill fish without any negative consequences. On the other hand, red claw crabs can get fungal and bacterial illnesses, as well as scavenging infestations. However, such situations are extremely rare.

Stress and a lack of space can increase red claw crabs being ill. Thus frequent water changes and careful monitoring of water temperature and habitats are strongly advised.

Facts About Red Claw Crab 

  • Perisesarma Bidens or a Red Claw Crabs is a phylum Arthropoda species situated mostly in the Asian continent. It comes from the Sesarmidae family.
  • The Red Claw Crabs feed on brine shrimp, worms, and fish.
  • Red Claw Crabs can be found in shallow rivers, estuaries with sea access, and aquariums. They’ve also been discovered in mud flats in parts of the South China Sea and Hong Kong seas going via Singapore, according to aquarists.
  • The red claw crab is often on land to get air, but it dehydrates easily and can’t sustain on land for long.
  • The Red Claw Crab feeds on its exoskeleton that’s been discarded after molting, which is a source of calcium.
  • The Red Claw Crab is usually shy and prefers spending their days hidden and being active at night.
  • They are quite defensive, extremely territorial, and their hunting behavior is mostly associated with their space rather than their food.
  • Red crab, (pseudo) Grapes bidens, Thai crab, Sesarma moeschi, Perisesarma bidens, Sesarma bidens, and mini crab are all names for the red claw crab.

Frequently Asked Questions (FAQs)

Are Red Claw Crabs Freshwater?

Red Claw Crabs are not freshwater crabs, contrary to popular assumption. Although these crustaceans can survive in freshwater, they will not live out their entire lives unless they reside in saltwater.

How Can You Make Brackish Water For Red Claw Crabs?

Because red claw crabs come from various environments, they can thrive in various settings. They grow in a humid climate with temperatures ranging from 68 to 75°F. A pH of 7.4-8.2 is their ideal water condition. You can prepare salty water for the red claw crabs with a tablespoon of aquarium or kosher salt per gallon.

Are The Red Claw Crabs Fully Aquatic?

Many people believe that red claw crabs are only found in water. However, this is not the case, and some animals require land access to avoid drowning. As a result, it’s best to have a semi-aquatic ecosystem with terrestrial animals and plants, as well as aquatic and semi-aquatic decorations.

How Do You Feed Vegetables To The Red Claw Crabs?

The vegetables should be safely provided to the crabs. Cucumber and zucchini should be rinsed under running water, peeled, and cut into pieces. After that, blanch the sliced pieces in boiling water for no longer than 3 minutes. 

Once the blanching is finished, plunge the vegetables into ice-cold water to stop the cooking process. After the cooling process is complete, feed the crabs once or twice a week, removing any uneaten pieces after one day to avoid dirtying the tank.

Do You Need To Install A Heater For The Red Claw Crabs?

Since Red Claw Crabs are tropical creatures, they require water temperatures of 22-27 degrees Celsius; therefore, if the ambient temperature is within this range, a heater can be omitted.

What Type Of Tank Mates Should Be Avoided For The Red Claw Crabs?

Red Claw Crabs prefer their own company. Because they are natural predators, anything slow-moving and bottom-feeding should be avoided. Turtles, snails, and dwarf frogs should not be kept in the same tank as the crabs since the turtles will eventually consume them. Fiddler crabs and dwarf shrimp are also required to be avoided.

What behavior do red claw crabs have?

It is really fun to keep red claw crabs as they are very fun to watch. Though they spent a lot of time hiding. But when they come out they can be very entertaining. Owners with a soil substrate will notice that these crabs like to show their natural scavenging behavior. When they meet a tankmate, be it a fish or another crab, they become defensive and raise their claws to scare the intruder.

Some hobbyists say that their red claw crabs lose fear of them after a while. But still, if you will need to take the crab to hand do not forget that they can pinch you.

Where to buy red claw crabs?

If you want to get some red claw crabs you can find them in your local fish store. You can get these crabs online. Some people complain that they could not find red claw crabs in any aquarium stores. But anyways in this case you can always choose the online shopping option.

Overall specifications

  • Origin – Asia
  • Other names – Perisesarma bidens, mini crab, Sesarma bidens or sesarma moeschi
  • Tank size – at least 60cm paludarium
  • Water type – Brackish water
  • Salt of water – should be around 1.005
  • Temperature – 72-82 F degrees
  • Breeding – Egg hatching and larvae, but almost impossible to do it at home
  • pH level – 7,5-8,5
  • Diet – Omnivore
  • Temperament – Aggressive

So, we can say that keeping red claw crabs can be both simple and challenging. Even though some of the difficulties red claw crabs are very fun to keep. The most difficult parts of keeping these crabs is the tank setup and the breeding. The tank has specific requirements which should be mimicking the natural habitat of red claw crabs. And if you will have a tank with all the required setups there will not be any other difficulties. As for the breeding, it is better not to think about it at all, as most probably you will not have any results. So if you have decided to get a paludarium of red claw crab, then good luck, and do not forget to have all the required factors for them to be happy and healthy.

4 thoughts on “Red Claw Crab: All the Information You Need”

  1. I just started caring for red claw crabs a few days ago, and the branches that I have in the tank for climbing and getting O2 are covered in a sort of clear but milky substance with tiny silver….eggs? I’m guessing one of my crabs mated at the aquarium I bought them from. Are we sure these eggs won’t hatch? AHHH

    • Hello, I am new to keeping red claw crabs as well though I have other aquariums and other types of crabs. I think what you could have been experiencing was more sap from the branches leeching out. Aquarium branches etc can look milky and pretty gross for the first few weeks in a tank. I try to pre-soak them for a long time before I put them in the tank and I will take them out and spray them down with hot water on occasion those first few weeks..


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