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Do Hermit Crabs Carry Diseases? (Common Illnesses to Know)

Do Hermit Crabs Carry Diseases? (Common Illnesses to Know)

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The purpose of this blog is to share general information and is written to the author's best knowledge. It is not intended to be used in place of veterinary advice. For health concerns, please seek proper veterinary care. In addition, as an Amazon Associate I earn from qualifying purchases.

Hermit crabs might be the perfect pets for you if you’re looking for easy-to-care-for, fun, and curious pets. These marine and land animals aren’t true crabs because they have exposed, softer abdomens and search for abandoned shells to protect themselves.

Before you decide to bring some hermit crabs home, you need to know how to care for them and how to protect yourself.

So, do hermit crabs carry disease? Can they make you sick?

We’ll answer these questions in our article, so keep reading to learn more about these fantastic pets.

Do Hermit Crabs Carry Disease?

Luckily, hermit crabs don’t carry any diseases that can be transmitted to humans.

These animals are clean and rarely become ill. In addition, they’re free from allergens that other pets might carry, so they’re perfect for people with allergies.

Yet, hermit crabs can suffer from stress or anxiety with changes in their environments, like moving the animal from one aquarium to another or introducing a new member to other hermit crabs.

These unfavorable situations can make a hermit crab sick because it’s unable to adapt.

Every about 18 months, hermit crabs molt and shed their original skin to rejuvenate their bodies. While doing so, they also avoid getting any long-term illnesses.

By shedding their skin, these small animals are able to get rid of any infection before it gets worse.

When there’s a problem with one of their legs or claws, the hermit crab will get rid of the infected limb. Hermit crabs are able to grow new legs while molting.

Can Hermit Crabs Get Sick?

Hermit crabs can suffer from several diseases, especially if you’re not feeding them properly or the aquarium isn’t kept clean. Moreover, introducing a sick hermit crab to an enclosure can infect other animals.

These health conditions will only infect hermit crabs but won’t be transferred to humans.

Shell Disease

When a hermit crab suffers from shell disease, you start to see some discoloration on the legs, claws, and abdomen.

Shell disease is caused by microorganisms that grow when the crab’s enclosure isn’t kept clean, or a new hermit crab that carries this disease is introduced to an existing group.

Through molting, hermit crabs are able to cure themselves by getting rid of the infected old exoskeleton.

As a pet owner, there’s nothing you can do but help your hermit crab stay in good shape to support healthy and successful molting. Here are some tips you can follow to keep your hermit crab comfortable.

  • If you notice a big bubble growing on the underside of the abdomen, then your hermit crab is about to molt. You need to make sure that the substrate is deep enough to provide the crab with the needed privacy.
  • The molting hormone is produced in the dark, and the freshly molted hermit crab will be unable to move until it has gained control of its muscles and its new exoskeleton has hardened up. So, avoid handling the crab or touching it.
  • If you’re worried about the larger crabs eating a molting one, you can set up an isolation tank inside the main one.
  • Enrich the crab’s diet with extra veggies and small pieces of meat to help with the molting process.
  • Mist the tank every day and keep a fresh supply of water and food.
  • Mix some sea salt with the fresh sand you add to the tank because the crab needs to store this salt in its body to grow a new exoskeleton.


Mites can usually infest your tank or aquarium upon the introduction of a new sick hermit crab or new toys that haven’t been well sterilized.

These small creatures won’t kill your crab instantly or transfer to you, but they can stress your hermit crab severely.

In very rare cases, if you don’t wash your hands after touching mites, they can cause a rash. Yet, normally, humans aren’t the preferred host of hermit crab mites.

Mites or fish lice are usually about 1/16 inches long and have eight legs. They could be red, amber, brown, or off-white.

They’re microscopic and hard to see, but you can detect them if you see tiny tan flecks moving on the shell of your hermit crab.

These parasites can make your hermit crabs and any other fish in your tank very sick. They feed on the blood of aquatic animals, and your hermit crab can lose a leg and eventually die if the condition is left untreated.

The best way to protect your hermit crabs from mites is to prevent their presence in the first place. This can be done by following these steps.

  • Always schedule routine cleaning to sterilize and clean all the tank’s components.
  • Smell any sponges that you keep for humidity and replace them if they smell rotten.
  • Clean any spoiled or uneaten food and remove it from the tank.
  • Replace the water and food and remove crabs’ droppings periodically.
  • Check your crab on a regular basis.

If you notice that your hermit crab is suffering from mites, you must follow these steps to eliminate them.

  • Place your crab in a holding container to clean its original tank.
  • Give your crab a bath in dechlorinated water. Turn it upside down to get into every part of the shell and drain the water.
  • Repeat the bath until the water runs clear and there are no more mites.
  • Empty all the contents of the tank and make sure that it’s dry.
  • If possible, get rid of all the tank accessories, including the substrate and toys. Once you put them in a garbage bag, get rid of the bag so the mites don’t crawl back into the tank.
  • If this is not possible, use distilled water to boil any tank toys or accessories for at least 20 minutes.
  • Any oven-safe accessories like sand or gravel can be baked in the oven at 300 degrees Fahrenheit for at least 90 minutes. Wood pieces can be sterilized in the microwave, but keep an eye on them, so they don’t catch fire.
  • If you’re still unable to get rid of the mites, ask a vet for a specific medication for hermit crabs.
  • Avoid using any detergent or bleach to clean the tank, as these chemicals can make the hermit crab sick.

Respiratory Problems

Land and marine hermit crabs need to keep their gills moist to breathe. Although land hermit crabs don’t survive underwater, they need to be surrounded by water to stay in good shape.

When the water in the tank isn’t chlorine-free, the gills become inflamed, and the blisters prevent the crab from breathing. This health condition can lead to suffocation.

To help the crab recover, you need to make sure that you’re using distilled spring water or dechlorinated tap water before adding it to the crab’s enclosure.

Losing Limbs

Losing a limb is a sign that your hermit crab is severely stressed.

In most cases, this happens after you bring a new hermit crab home because it was stressed during the moving process. However, it can also happen because of an injury.

Hermit crabs sometimes lose limbs because of a stressful situation that has been introduced to their environment, like insufficient water or food, improper sun exposure, or a fluctuation in the temperature or humidity levels.

If you notice that your hermit crab is losing its legs, then pay attention to any recent change in its environment.

Crabs are usually able to recover by growing new limbs.

Are Hermit Crabs Venomous?

There are about 800 species of hermit crabs, and most of them are marine animals. None of these species is venomous.

As a matter of fact, all crustaceans, except Speleonectes tulumensis or cave swimmers, aren’t venomous. The good news is that no one keeps those hermaphroditic crustaceans as pets.

However, this doesn’t mean that hermit crabs aren’t dangerous at all.

If you’re not careful while handling the crab, it might pinch you. The wound might not be too deep, but you still have to disinfect it using soap and alcohol.

Remember that although hermit crabs aren’t dangerous, they live in a dangerous environment. The bacteria from the water or enclosure can cause a severe infection if a wound is left unattended.

Can Hermit Crabs Make You Sick?

Generally speaking, hermit crabs won’t make humans sick. They don’t carry any diseases that can be transferred to humans, and they’re not venomous.

However, hermit crabs live in an environment that is usually filled with microorganisms and pathogens.

The moist habitat of the crab is an environment where bacteria and fungi flourish.

This is why you need to take a few precautions while handling a hermit crab or cleaning its enclosure.

  • If you’re bringing hermit crabs from the wild, make sure that they go through a quarantine period.
  • Wear gloves while handling your crab, especially if it’s a new one. This will protect you from potential pathogens and will also protect the crab’s delicate limbs.
  • Routinely clean the enclosure by removing old food and water.
  • Wash and sanitize any items you introduce to the tank, like toys, driftwood, or plants.
  • Clean and sanitize any shells you add to the enclosure.
  • Don’t leave a dead hermit crab in the tank for too long.

Do Hermit Crabs Carry Salmonella?

Hermit crabs don’t carry or transmit salmonella. This is good news, especially if you want to have a safe pet that your little ones can play with.

Unfortunately, this isn’t true for other crabs. Other crustaceans, including true crabs, are carriers of salmonella that can infect humans.

Humans who get infected with salmonella can suffer from several annoying symptoms.

  • Diarrhea and other digestive issues.
  • Vomiting.
  • Night chills and sweating.
  • Fever.
  • Abdominal pain.

The bacteria can be present in other pets, like lizards and turtles, but they’re not present in hermit crabs.

Can Hermit Crabs Get Ich?

Marine ich is one of the most common diseases that infect marine animals. Fortunately, ich isn’t interested in infecting hermit crabs because they lack the biological component that these parasites need to reproduce.

Ich only affects fish, but hermit crabs can be carriers of these annoying parasites.

Ich parasites have evolved to survive for long periods outside the body of their main host, so they can attach themselves to the hermit crabs’ shells. They also thrive on any other surface, like plants, snails, rocks, gravel, and toys present in a tank.

This is why it’s essential to quarantine a new hermit crab before adding it to an established fish aquarium, as it might make the other fish sick.

Usually, keeping the new crabs in an isolated tank for a couple of weeks is enough if you’re not sure that they’re carrying any parasites. If you’re certain, you can keep them in quarantine for up to 9 weeks.

There are two types of ich, freshwater and marine water ich. Both types can infect your fish if you add parasite-carrier hermit crabs to the tank.

Keeping new hermit crabs in an isolated tank where there’s no access to fish will eventually kill the ich parasites. Reef-safe hermit crabs are known to belong to what aquarists call the clean-up crew, also known as CUC, and they’ll help get rid of the ich.

If you notice that your saltwater fish are growing white spots because of ich, you can give them a freshwater bath. This can usually relieve any discomfort and help the fish recover.

In the case of freshwater fish, you might think about adding some sea salt to the freshwater tank to kill freshwater ich. However, this is too risky as freshwater fish are less tolerant of salt.

Final Thoughts

Hermit crabs get infected with some diseases, but they don’t transfer these diseases to humans. In addition, they’re free of allergens and are not venomous, so they’re perfect pets for people with kids.

Most hermit crabs suffer from diseases because of stress or neglect. By providing your pet crab with a balanced and healthy diet and keeping its enclosure clean, the animal will stay healthy.

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