Rainbow Crab Care 101: Coloration, Size, Habitat |Updated|2024

The Rainbow Crab is a species of land crab native to the tropical forests Western Africa. These crabs are brightly colored, with a purple-blue carapace and orange-red legs. They are also quite large, reaching up to 4 inches in width.

This is a famous pet crab, but they are not suitable for everyone. These crabs are aggressive and can be very territorial. They also require a specialized diet and a large tank. If you consider getting a Rainbow Crab, please read this complete care guide first.

This guide will teach you everything you need to know about caring for beautiful Rainbow Crab.

Species Summary

Scientific Name:	Cardisoma armatum
Common Names:	Rainbow Crab, Blue Land Crab, Scarlet-legged Crab
Adult Size:	3-4 inches
Life Expectancy:	Up to 8 years
Care Level:	Easy-medium
Temperament:	Aggressive
Diet:	Omnivore
Family:	Gecarcinidae
Tank Size:	At least 20 gallons
Tank Type:	Paludarium
Water Temperature:	Between 75° to 85° F
Water pH Level:	7.0-8.5
Water Hardness:	8-12 dGH
Compatibility:	Not compatible with other species

Rainbow Crab Appearance

The Rainbow Crab is a large land crab with a purple-blue carapace and orange-red legs. The carapace can reach up to 4 inches in width, while the legs can be up to 6 inches long. These crabs are sexually dimorphic, meaning the males and females look different.

Males have larger claws than females, and their abdomens are more rounded. Females have smaller claws and a more angular abdomen. Males also tend to be more brightly colored than females.

The Rainbow Crab is sometimes confused with the Blue Land Crab (Gecarcinus lateralis). These two species are very similar in appearance, but the Rainbow Crab has orange-red legs while the Blue Land Crab has blue legs.

The Rainbow Crab is sometimes confused with the Scarlet-legged Crab (Gecarcinus ruricola). These two species are again very similar in appearance, but the Scarlet-legged Crab has red legs while the Rainbow Crab has orange-red legs.

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Rainbow Crab Lifespan

The Rainbow Crab has a lifespan of 3-4 years in captivity. In the wild, these crabs can live up to 8 years.

How Much Does It Cost And Where Can I Buy Them

Rainbow Crabs typically cost between $10 and $20. They can be bought online or at a pet store.

Predators

In the wild, the Rainbow Crab’s predators include snakes, lizards, birds, and mammals.

In captivity, their only predator is you. These delicate crabs can be easily killed by handling them too roughly.

Are They Dangerous

Rainbow Crabs are not dangerous to humans. They can, however, give you a nasty pinch if they feel threatened.

It is also important to note that these crabs are very sensitive to environmental changes. Sudden changes in temperature or humidity can cause stress and make them sick.

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How Do I Know If My Crab Is Healthy

A healthy Rainbow Crab should be a bright purple-blue color. Their legs should be orange-red, and their claws should be a dark brown or black.

If your crab is not eating or is losing color, this could be a sign of illness. It would help if you took them to a vet who specializes in reptiles and amphibians to have them checked out.

Rainbow Crab Size And Growth Rate

Rainbow Crabs reach a adult size of 3-4 inches. These crabs grow quickly, reaching sexual maturity at 5 1/2 to 6 inches.

Rainbow Crab Behavior And Social Temperament

Rainbow Crabs are very active and love to explore their tank. They are also very hardy and resistant to disease.

These crabs are not social animals. They are quite aggressive towards each other. They will only tolerate each other when they are ready to mate. After the mating process, the male and female will separate.

You should only keep more than one Rainbow Crab together when trying to breed them. If you have more than one male or female, they will fight each other for dominance.

Rainbow Crabs are also known to be escape artists. They are very good at digging and can easily climb out of their tank. For this reason, it is important to ensure their tank is secure.

Rainbow Crab Care Guide

Here, we will discuss all important things to give best care to your Rainbow Crab.

The Rainbow Crab is an easy-medium care level crab. They are a hardy species that is resistant to disease. These crabs are also very active and love to explore their tank.

Providing them with the proper diet and housing will make them happy and healthy.

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Rainbow Crab Tank Set Up

The Rainbow Crab is a land crab, so they need land and water to survive. The best way to provide them with both is to set up a paludarium.

A paludarium is half land and half water. It can be as simple as a 10-gallon aquarium with mesh or glass separating the two halves. The land portion should be at least 5 gallons.

The land portion of the tank should be filled with a substrate that holds moisture well. Coconut husk fibers, sphagnum moss, and potting soil are all good options. The substrate should be 4 inches deep so your crab can burrow.

The water portion of the tank should be shallow enough for your crab to walk through. A depth of 2-3 inches is ideal. Depending on what your crab prefers, this area can be filled with freshwater or saltwater.

The water should be filtered and changed regularly to keep it clean. It is also a good idea to add some plants to the water portion of the tank. This will help keep the water clean and provide your crab with a place to hide if needed.

The land portion of the tank should be kept moist but not wet. You can do this by misting the substrate with water every day. The humidity in the tank should be kept between 75% and 85%.

You should also provide your crab with hiding places on their tank’s land and water portions. A piece of driftwood, a cave, or a flower pot turned upside down are all good options.

Your crab will also need a heat source to keep their bodies warm. An incandescent light bulb or a ceramic heat emitter will work well. The temperature in the tank should be kept between 75° to 85° degrees Fahrenheit.

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Rainbow Crab Breeding And Reproduction

Rainbow Crabs are ready to mate at 3-4 years of age. When they are ready to mate, the male and female will go through a courtship ritual. The male will drum his claws on the ground and wave his arms to get the female’s attention.

If the female is interested, she will allow the male to approach her. The two crabs will then rub their bodies together and exchange pheromones. After the courtship ritual is complete, the female will lay her eggs. She will keep them safe in her abdomen until they are ready to hatch.

Once the eggs have hatched, the young crab will be alone. They will not receive any help from their parents. Rainbow Crabs can only be bred with other Rainbow Crabs. They are not compatible with any other species.

How Difficult Is To Breed

Rainbow Crab breeding is not difficult. However, it can be hard to find a compatible mate. These crabs are very territorial and will only breed with other Rainbow Crabs.

It is also essential to ensure that males and females are of different sizes. The male may harm or even kill the female if they are the same size.

You should also only keep one male and one female together. If you have two males, they will fight each other for dominance. If you have two females, they may not get along well either.

Rainbow Crab Gestation Period

The gestation period for Rainbow Crabs is about 8 weeks. The female crab will carry her eggs in her abdomen during this time.

Once the eggs have hatched, the young crab will be alone. They will not receive any help from their parents. The only way to tell if a Rainbow Crab is pregnant is by looking for eggs in her abdomen. If you see any eggs, the crab is pregnant and will soon lay them.

If you want to know, you can take the crab to a vet specializing in reptiles and amphibians. They will be able to confirm if the crab is pregnant and when she is due to lay her eggs. Rainbow Crabs can have up to 100 offspring at a time. However, the average number of offspring is between 10 and 20.

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Feeding The Baby Crab

Once the young crab has hatched from its egg, it will be on its own. The parents will not help to care for them. The young crab will need to find its food and shelter.

As they grow, the young crab will molt their exoskeleton. This process can take up to 6 weeks. During this time, the crab will be very vulnerable. They will not have their hard shell to protect them from predators and the elements.

After the crab has molted, they will need to eat a lot of food to help them grow their new shell. Once they have their new shell, they can return to their normal diet.

How Rainbow Crab Different From Other Crabs

Rainbow Crabs are different from others because they are active and love exploring their tank. They are also very hardy and resistant to disease.

Another difference is that Rainbow Crabs can only be bred with other Rainbow Crabs. They are not compatible with any other species. Finally, the young crab will be on its own after it hatches from its egg. The parents will not help to care for them.

Rainbow Crab Tank Size

The minimum tank size for a Rainbow Crab is 20 gallons. However, if you want to keep more than one crab, you need a larger tank.

The bigger the tank, the better. This will give the crabs more room to explore and help prevent them from fighting each other.

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Rainbow Crab Tank Mates

Rainbow Crabs are not compatible with other species. They are aggressive and fight with other crabs, shrimp, and fish. They do not like any tank mates of different or similar species.

Rainbow Crab Tank Decorations

Rainbow Crabs are very active and love to explore their tank. They are also good climbers. For this reason, it is important to provide them with plenty of places to hide and climb.

Some good decorations for their tank include driftwood, rocks, and live plants. These decorations will also help to create a more naturalistic environment for your crab.

Driftwood and rocks can be used to create hiding places and climbing structures. Live plants can help to filter the water and provide a place for the crab to hide.

Substrate

The best substrate for Rainbow Crab is sand. This will allow them to dig and burrow easily. It is also soft on their claws.

Other substrates that can be used include gravel and pebbles. However, these substrates can harm the crab if they eat them.

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Water Quality

It is essential to maintain good water quality in the Rainbow Crab tank. These crabs are very sensitive to changes in water quality.

The best way to maintain good water quality is to do regular water changes. A water change of 10-15% should be done every week.

You should also regularly test the water for ammonia, nitrites, and nitrates. Ammonia and nitrites are very toxic to crabs and can kill them quickly.

The ideal water temperature for Rainbow Crab is 75° to 85°Fahrenheit.

The ideal pH level for Rainbow Crab is 7.0-8.0. If the pH levels drop below or rise above this range, it can harm the crabs.

The ideal water hardness for Rainbow Crab is 10-20 dGH. If the water hardness drops below or rises above this range, it can harm the crabs.

The ideal salinity for Rainbow Crab is 1.023-1.025. If the salinity levels drop below or rise above this range, it can harm the crabs.

Ammonia should be tested regularly to ensure that they are not rising. The ammonia levels should be kept between 0 and 0.5 ppm.

Nitrites should be tested regularly to ensure that they are not rising. The nitrite levels should be kept between 0 and 0.5 ppm.

Nitrates should not exceed 40 ppm. If the nitrates rise above this level, you should do a 10-15% water change.

Oxygen levels should be kept between 5 and 7 ppm. Sufficient oxygen ensures that the crabs will have enough oxygen to breathe.

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Heater

A heater is not required for Rainbow Crab tanks. However, having one on hand is a good idea in case the water temperature drops.

Filter

A filter is not required for Rainbow Crab tanks. However, having one on hand is a good idea in case the water quality drops.

Lighting

Rainbow Crab tanks do not need special lighting. A simple aquarium light will suffice.

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Placement

Rainbow Crab tanks can be placed anywhere in your home. They do not need special lighting or temperature requirements.

Gravel Vacuuming

Gravel vacuuming is not required for Rainbow Crab tanks. However, doing this every week is a good idea to help maintain good water quality.

Substrate Heating

Substrate heating is not required for Rainbow Crab tanks. However, a heater is a good idea if the water temperature drops.

Protein Skimmer

A protein skimmer is not necessary for Rainbow Crab tanks. However, it can help to remove some of the waste from the water.

Rainbow Crab Food & Diet

The Rainbow Crab is an omnivore, meaning they eat plants and animals. In the wild, these crabs scavenge for food. They will eat just about anything they can find, including dead leaves, insects, and small vertebrates.

In captivity, these crabs should be fed a diet of fresh vegetables and fruits and various meaty foods. Some good vegetables for Rainbow Crabs include kale, collard greens, and squash. These crabs also enjoy fruits like mango, papaya, and grapes.

You can feed your Rainbow Crab cooked chicken, shrimp, or beef for meaty foods. You can also give them live foods like crickets, earthworms, and mealworms.

You must offer your crab various foods to ensure they get all the necessary nutrients. A good way to do this is to create a buffet-style setup in their tank. This way, they can choose what they want to eat.

You should also offer your crab a calcium supplement to help them keep their shells strong. A cuttlebone is a good option, as it will also provide them with extra calcium.

How Often Should I Feed Them?

Rainbow Crabs should be fed once or twice a day. The amount of food you give them will depend on the size of your crab. A good rule of thumb is offering them as much food as possible in one sitting.

You can also offer your crab food every other day. This will help keep their tank clean and prevent mold and bacteria from growing.

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Diet Foods To Avoid

There are some foods that you should avoid feeding your Rainbow Crab. These include chocolate, caffeine, and alcohol. These foods can be toxic to crabs and can cause serious health problems.

You should also avoid feeding your crab processed foods, as these are not good for their health.

What Do They Drink?

Rainbow Crabs get the majority of their water from the food they eat. However, you should also offer them a freshwater source. This can be in the form of a bowl, bottle, or sponge.

The water should be changed regularly to prevent it from getting dirty.

Freshwater Aquarium Plants

Rainbow crabs are not known to eat plants. However, they may uproot them while looking for food. Choosing hardy plants that can withstand abuse is best if you want to keep plants in your Rainbow Crab tank. Some good options include Java Fern and Anubias.

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Potential Diseases

Rainbow crabs are relatively hardy and do not often get sick. However, there are a few diseases that they can be susceptible to.

• Bacterial Infections
• Fungal Infections
• Stress
• Shell Rot
• Parasites
• Molting Problems

Preventing Disease

The best way to prevent disease is to keep your Rainbow Crab tank clean and free of stressors. You should also quarantine new crabs before adding them to your tank.

If you think your crab is sick, you should take them to the vet for treatment.

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Treatment And Medications For Diseases

You should take your crab to the vet for treatment if your crab is sick. They will be able to prescribe the proper medication for your crab.

Some common medications used to treat Rainbow Crab include antibiotics, antifungals, and antiparasitics.

• Tetracycline: This antibiotic is used to treat bacterial infections. It is used to treat infections such as columnaris and mycobacterium.
• Metronidazole: This antibiotic is used to treat bacterial infections. It is used to treat infections such as giardia and trichomoniasis.
• Clindamycin: This antibiotic is used to treat bacterial infections. It is used to treat infections such as staphylococcus and streptococcus.
• Ketoconazole: This antifungal is used to treat fungal infections. It is used to treat infections such as candida and dermatophytes.
• Fluconazole: This antifungal is used to treat fungal infections. It is used to treat infections such as candida and dermatophytes.
• Ivermectin: This antiparasitic is used to treat parasitic infections. It is used to treat infections such as scabies and lice.
• Levamisole: This antiparasitic is used to treat parasitic infections. It is used to treat infections such as hookworms and roundworms.
• Fenbendazole: This antiparasitic is used to treat parasitic infections. It is used to treat infections such as giardia and coccidia.
• Praziquantel: This antiparasitic is used to treat parasitic infections. It is used to treat infections such as schistosomiasis and flukes.
• Copper Sulfate: This is a medication that is used to treat shell rot. It is applied to the affected area of the shell.
• Erythromycin: This medication is used to treat shell rot. It is applied to the affected area of the shell.
• Prednisone: This medication is used to treat molting problems. It is given to the crab orally.

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Advantages Of Having Rainbow Crab In Your Tank

• They are interesting to watch: Rainbow Crab is very active and interesting to watch. They are constantly moving around and exploring their tank.
• They help keep your tank clean: Rainbow Crab is a scavenger and helps keep your tank clean. They will eat leftover food and decaying matter.
• They are good at controlling algae: Rainbow Crab is known for their ability to control algae. They will eat algae off of rocks and glass.
• They provide oxygen: Rainbow crabs provide oxygen to the water through their gills. They help to aerate the water and keep it clean.
• They are easy to care for: Rainbow crabs are relatively easy. They are hardy and can tolerate a wide range of water parameters.
• They are low maintenance: Rainbow crabs are low maintenance and do not require much care. They can live in a small tank and do not need much attention.
• They are inexpensive: Rainbow Crab is very inexpensive and is a great addition to any tank.

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Disadvantages Of Having Rainbow Crab In Your Tank

• They are escape artists: Rainbow Crab is known for their ability to climb and escape from tanks. They should be kept in a tank with a tight-fitting lid.
• They can be aggressive: Rainbow Crab can be aggressive towards each other and other tank mates. They should be kept with fish that are too large to be eaten.
• They are destructive: Rainbow Crab can be destructive to plants and decorations in the tank. They should be kept in a tank with sturdy plants and hideaways.
• They are messy eaters: Rainbow Crab can be messy eaters and make a mess of the tank. They should be fed in a separate tank or a feeding station.
• They carry diseases: Rainbow crabs are known to carry white spot and red claw disease. It is important to quarantine new crabs before adding them to your tank.
• They can be difficult to catch: Rainbow Crab can be difficult to catch and remove from the tank. They should be kept in a tank with a tight-fitting lid.
• They are not recommended for beginners: Rainbow Crab is not recommended for beginners. They require a lot of care and attention. It is best to leave them to experienced aquarium keepers.

Conclusion

Rainbow Crab is a great addition to any tank. They are interesting to watch and help keep the tank clean. They can be a bit aggressive and destructive but are overall low maintenance. They are known to carry diseases, so it is important to quarantine new crabs before adding them to your tank.

Rainbow Crab is not recommended for beginners. It is best to leave them to experienced aquarium keepers. Thanks for reading!