The red claw crab is a passionate little red crawler from the mangroves; you can get it as a home pet.

These are one of the 23 recognized species belonging to the Sesarmidae family. Scientifically termed as Perisesarma Bidens (first found in 1835), they are typical semiterrestrial crustaceans that use gill chambers to fetch oxygen from the pre-stored saline water while on the mud surface.

Commonly known as mini crabs, these are small-sized creatures that prefer to stay near the coastal regions and are ready to eat everything that comes in front. 

Having these red claw crabs in your aquarium gives an esoteric perception to the visitors, which is one reason why marine lovers wish to learn the ways to keep them growing in their home display glass.

Here is a quick guide on red claw crab, briefing how to care, breed, and pet them in home tanks.

Lets’ Know More About the Crab

Species Specs.
Scientific Name Perisesarma Bidens
Other Common Names The Red Crab, Sesarma Moeschi, Mini Crab
Family Sesarmidea
Origin Indo-Pacific zone
Lifespan Three years maximum
Size 2.5 inches
Type Freshwater

Habitation and Origin

The red-clawed crabs are deeply rooted in the Asian mangroves, which are their favorite dwelling places.

These crabs prefer to stay in brackish waters or the shallow swamps around the coastlines. Researchers have even addressed the bulk of traces in the mudflats in many south-east Asian countries.

Note: Here, the confusion arises if the red claw crabs are freshwater or saltwater habitats, but the fact is that the mangroves grow in freshwater, but being on the edge of the sea, contains some amount of salinity.

While staying in the natural habitation, these crabs move towards the freshwater that meets the sea. The salinity of the ocean gets in combination with the freshwater to form the brackish.

This saltwater combination is hard to maintain artificially, and hence it becomes challenging to create favorable conditions locally for these crabs.

Maximum Size

These are generally considered low-sized crawlers, having a carapace of around 5cm. In addition to that, the maximum length of its legs when they are expanded is about 10cm.

It is observed that there is a size difference between the male and female species of this crab, the male being a bit more in length than the female.

The red crabs analytically are not too giant like other crabs, and hence they look lesser dangerous in-home environment. Petting these tiny creatures is easy and safe while retaining the beauty of the place.

Red Claw Crab Care - Pet Them in Home Tanks

Appearance and Color

The essential feature in their appearance is the charming reddish coloration that naturally catches attention. The eyes look elongated further from the head as if it is a headlight.

They only walk with eight legs out of the ten legs available. The other two are the claws that it uses to grab the food. These claws look elegant in an orangish shade over a shiny red combination.

The crab’s body is covered with big and small patches giving it a unique appearance, and these specific color shades differ from each individual.

Max Life Expectancy

The average life of this crab when being in the wild is relatively high compared to those living in aquariums. These are generally sensitive to water conditions and do not readily settle down to changes.

The red claw crab lives up to 2.5 years if kept in an aquarium, but this is still not easy as you need to match the unique water requirements.

These crabs prefer brackish water, and artificially salty water rarely reaches their choice. Fewer things fulfill their demands tend to lose interest and live a short life.

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Gender Identification

Like most marine life, it is hard to signify the gender of the crabs. The most noticeable difference is through color matching, which is a comparative answer rather than straight identifiers.

Here are the fundamental differences in gendering.

  • The males of these crabs are more brilliantly colored, while the females present a dull shade.
  • The male’s body and claws are more significant in size as compared to the females.
  • The claws in the females are a bit dark red, while in males, it is shinning orange or yellowish.
  • The underneath flap in the males is thin & sharp, while in females, it is wide.

Prolonged research in gendering crabs has found a significant change in the structure of male & female species. The carapace was studied using a geometric morphometric technique.

They found that the males have elongated anterior in both ways, while females had either narrowing or widening of caudal, frontal fins & carapace breadth.

Selling Price & Availability

The red claw crabs are found in a wide range around the sea coasts of Asia, and hence they are sold and purchased worldwide by hobbyists.

It is available on-demand, and people can order their choicest pair from online/ offline stores. Considering the price variation in the market by different sellers in countries, the average cost of the red-clawed crab is around $12 to $17.

Care Guide: Red Claw Crab

Quick Care Points
Care Level Medium
Social Territorial
Temperament Hostile
Diet Omnivore
Breeding Pretty Difficult
Size 4 inches (with legs expansion)
Color Combination A mix of red and orange with brownish spots

Food & Diet

The red claw crab’s diet consists of everything they can hold in their mouth. These are typical omnivore predators that use their sharp claws to capture the food of choice.

These crabs attack slow movers in the water, primarily small fishes and worms living on the surface.

Author Note: The red crabs are habitual of eating their exoskeleton, discarded out of their body after the molting process. These exoskeletons are rich in calcium.

While being in their favorite locations of mangrove forests, the crabs pluck the leaves and feed over them. Other than that, they consume both meat and vegetation of all sorts.

Suggestive diets for red claws may include mineral-rich foods from the following list.

  • Boiled Pass
  • Spinach
  • Green leafy vegetables
  • Algae
  • Detritus
  • Microbes
  • Blood worms
  • Mollusks
  • Crustaceans
  • Zooplankton
  • Fish
  • Shrimps
  • Pellets (preferably algae forms)
  • Flakes
  • Mangroves

General Behavior

The red crawl crabs are highly hostile creatures that are possessive about their territory and may readily engage in vicious battles with co-males to claim their zones and, of course, their mating partners.

The two large claws are used as weapons to cramp the enemies, while if the potential risk is high, they quickly run into the caves, burrows, or any other safe place.

Another defensive technique they use is raising their claws in attacking mode, threatening the predator. The red crabs generally stay in their caves all day and come out for hunting during the night.

They can swiftly climb using their eight legs and crawlers and regularly come up to the surface for breathing. They can even climb the tank walls with extensive abilities, so keeping the lid over the exit is necessary.

Pro Tip: Do not get close to the red claw crabs as they can bite you, but do not worry if you get bitten as, unlike many other crabs, these are not poisonous to feel the pain, but the wound is not fatal.

Breeding

The red crawl crab is a seasonal breeder and reproduces from April to September.

These crabs are overparticular about their breeding environment, and it is hard to impossible to make them mate in an artificial setup.

However, few experienced breeders create natural settings for these crabs. These are too sensitive to environmental conditions, and a slight change may ultimately damage the situation. But there is always a risk-prone situation for eggs to get rotten without hatching.

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Tank Setup for Breeding

Take a separate tank of approx. 100 liters capacity, and put sand as the substrate with some air stones or pebbles. Add salt and water to the tank in one-liter water to one spoon salt.

Maintain the gravity at 0.01ppm, with optimum warmth, nutritious food, and dim light arrangement. Put some object into the tank using which the female crab can walk out on its own after laying eggs.

Mating

The female crabs can mate more than three times in a season and produce 300 eggs each time. The eggs get attached to the stomach of the female crab for 18 to 20 days until they are ready to hatch.

Monitoring eggs is easy as they have a pre-set color change sequence from initial red to grey in the end. The female crab moves out of the tank after they hatch.

Quick Tip: The crab females produce eggs that get hatched after laying them, but like most marines, the crab parents tend to eat the larva from those eggs; hence it is essential to protect the eggs while breeding.

Crab Larva

Once the red claw crab eggs successfully hatch to produce larva are ready to be fed with fluid artemia, and during this time, try to keep the water steady.

The larva keeps changing its appearance every third day and gets ready to hunt soon. In a few weeks, the larva starts looking like an adult crab.

Author Note: The initial larva stage is highly vulnerable, and most of them die at an early stage. So keep removing the dead larva before it contaminates the water. Do check the nitrite and nitrate level in the water, as an excess of it can be fatal.

Common Diseases

Keeping an attitude of eating everything, they expose themselves to several bacterial and viral infections. But the red crabs are pretty robust health-wise, and they do not quickly get troubled due to food or climatic disorders.

Pro Tip: Sometimes, an opening circle appears on the crab shell. If not removed from the body, it may form tendrils to fetch nutrition from the crab. It may look like a disease, but it can only be a barnacle, a harmless kind of parasite that attaches itself to the rugged rocks or shells.

In some cases, if they catch up some illness through parasitic diseases. It takes lesser time for the crabs to get recovered. Other than that, there are no severe health issues that require special attention.

Another aspect is that these crabs prefer to stay alone, and hence a small space or more number of marines in the tank may eventually increase their stress level, which may lead to some illness.

Tank Setup

Tank Specification
Capacity 40 to 50 Litres
Water Temperature 80 to 90 F
Hardness 9 to 26 dGH
Light Normal lighting
pH Level 7.5 to 9
TDS 150 to 200
Tank Water Quality Salted water
Nitrate Below 40ppm

Approximate Tank Size

The red crawl crabs are small to medium-sized crustaceans and can adjust in a standard-sized tank with a minimum capacity of 10 Gallons.

Despite their small stature, these crabs require a lot of space to sustain and grow. With extra room in the tank, you can easily install the substrates, plants, and other accessories that attract crabs.

This is an optimally suggestive tank size for one crab couple. However, if you are planning a group of these crabs, increase the capacity accordingly.

Tank Interiors

A pre-designed space with natural and mimicked structures is always better for a healthy habitat than providing a blank, barren water fill. Check out the feasibility of following the given setup ideas.

Plants

Planting natural greens in an aquarium is a great choice, as the tank creatures feel at home and live in a habitual terrain.

In the case of these red crabs, you may enroot a few plants (java fern are their favorite) in a space, but there are high chances they get plucked out by the crab.

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Word of Advice: They use the claws to grab an object, and dis-routing a plant is part of their playful activity. Artificial plants are a better alternate choice instead.

Lighting

These crabs do not like lights as they are nocturnal, and most of the daytime is spent in caves. But still, lights are essential for a healthy metabolism so that you can put up a few tank bulbs with usual dim to standard lighting.

Substrate

The perfect substrate to begin filling the tank is sand. Red claw crabs are chronic scavengers over sands and enjoy making caves in the tank bottom.

You can create a cave-like structure using pebbles and rocks to give them a hiding space, which they usually need during stress.

Crabs are used to traveling to landmasses frequently, so you can create a high altitudinal surface using mud and stones.

Oxygenation & Tank Filtering

Both water filtration and oxygenation are simultaneous processes. The water change in the tank shuffles the inner gases while creating space for oxygen.

Using a filtration system for water and air makes it easier for the keepers as it is more suitable and dependent, and at the same time, pets in the tank get a reliable solution.

Quick Tip: Air stones are an excellent alternate choice to help oxygenate the tank’s water.

Decor

Apart from the above-given items, you can put some small aquatic toys and objects that will keep the crab engaged. You can create steps for the crab to reach the top (keep the lids closed) or use some other creativity.

Water Parameters

Creating suitable water conditions for the red crawl crabs is pretty complicated. Although being freshwater types, they prefer to stay in the brackish portion of the river.

Considering this fact, though they are accessible to pets, you must carefully study the required water parameters before bringing them home.

They survive better in saltwater than freshwater, which is difficult to achieve. You can add up to 15 tablespoons of salt in a 10 Gallon tank or maintain this ratio, whatever is the tank size.

The other conditions are water pH between 7 to 9, approx—water temperature 20 to 25 degrees Celcius, and water hardness to be 10 to 25 dGH.

Tank Mates

The red crawl crabs are not too friendly; instead, they may get irritated by other swimmers in their territory.

Two male crabs of these species cannot live together in the same tank as they both may fight till the end. But one male usually pairs with two females, and hence these three can stay together.

Other marines have a high risk of getting killed by the crab. However, few creatures can be considered ideal mates to them.

  • Neon Tetras
  • Mollies
  • Guppies

Frequently Asked Questions

What is the molting process in crabs?

The red crawl crab has to undergo a molting phenomenon during which it has to lose its exoskeleton, and the soft skin takes time to harden.

How much time do the crabs take to molt?

Molting is a bit long process and takes about two weeks to complete. At this time, these crabs lookout for a safe hiding space, whether it is an open or closed area. They should not be disturbed during this period.

At what speed can these crabs run?

There is no recorded data available regarding the running speed of the crabs. However, they are observed to run at a rate of 18Kmph.

Can these crabs live in freshwater?

They cannot live in any other water other than salted water for a very long time. Crab’s body demands salinity, and hence they can stay in freshwater for some time but will start getting uneasy after some time and look for a change.

For how much time can they stay underwater?

Crabs are aquatic and can stay underwater for a long time. But they prefer to come up to the surface quite often, and hence they are seen staying close to the shore.

The Takeaways

Red claw crab is undoubtedly a crustacean in demand by many aquarists because of their brilliant reddish coloration and more enormous claws.

Though living for a short lifespan, they live an easy life without much maintenance needed regarding health issues. But of course, providing brackish water is necessary if you pet these animals.

Since they eat whatever they think is food for them, prefer not to keep them with other pets in your tank, or else there are chances of them becoming food of the crab.

About the Author

Victoria Lamb

Victoria is a freshwater aquatics specialist, fish keeper, and amphibian enthusiast. She has had more than 6 years of experience caring for aquariums and keeping several fish species, and her home boasts of 3 aquariums and a garden pond. Her goal is to educate fish owners on raising healthy and happy aquatic pets.

Career Highlights:

  • Has worked with several aquarium manufacturers as a consultant
  • Organized and hosted workshops on freshwater fish keeping at retail stores, educational facilities, and libraries
  • Released content for the amphibian community through her writings

Educational Highlights:

Bachelor of Science in Animal Behavior and Welfare

  • University of Lincoln, Lincoln, UK (2014-2018)

Writing Experience

Victoria has done ghostwriting for many aquarium and pet websites in the past. She has also worked for Canada's largest natural health magazine- ALIVE, with 300,000 monthly circulations as a freelancer. She had six published articles on animal behavior and welfare during her graduation for her thesis.

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