Why Do Hermit Crabs Die? Uncover the 15 Hidden Hazards and How to Protect Your Hermie


by Simon Griffiths



I am a frequent visitor and contributor to some of the big hermit crabs forums and online groups. While I enjoy seeing cute photos of hermies, my heart drops every time I see a member mourning their hermie.

And it happens every other day.

And if you follow up on the cause, it’s mostly from something that could have been avoided.

This post answers in detail the dreaded question – Why do hermit crabs die? With this information, you will be able to take better care of your pet hermit crab and eliminate avoidable deaths.

Why Do Hermit Crabs Die?
A photo with screenshots of hermit crabs owners reporting the death of their hermit crabs.



Why Do Hermits Crabs Die?

There are multiple reasons why hermit crabs die including post-purchase stress, wrong temperature, and humidity levels, unsuccessful molt, not providing saltwater and freshwater waters, and attack and bullying from other hermit crabs. Also, pets such as wrasse also kill hermit crabs. 

Knowing the common causes of hermit crabs’ death is the only way you can save other crabs from dying.

Why Did My Hermit Crab Die?

1. Post-Purchase Stress

why did my hermit crab die

Hermit crabs being sold in a store (Source: Reddit)

The most common cause of hermit crabs’ death is post-purchase stress. That’s why most deaths occur within the first month after bringing them home.

Post-purchase stress refers to stress due to a change in the environment. If the hermit crab was caught in the wild, the new life in the tank will be unfamiliar and may struggle to adjust, which can lead to death.

Store-bought hermits also face this challenge. Most of the time, the conditions in the store and the new conditions in the new tank differ. This is mostly the temperature and humidity levels. Also, make sure the hermit has everything else they need.

How to prevent post-purchase deaths?

The first thing to do is to ensure that the hermit crabs you are buying are healthy. Healthy hermits have a high chance of adjusting to the new environment. Weak and diseased hermits will struggle to adjust to the new environment. 

This one is key:

Another way to prevent post-purchase stress deaths is replicating similar conditions to where you bought them. This means, don’t introduce the new hermit crabs in the tank right away. Even if you have the perfect conditions.

The right way is to replicate the conditions in the store and then gradually slowly adjust the conditions.

For instance, if the humidity levels in the store were about 55% increase the levels by 5% every week until you attain the recommended 75-80%. This will help the crabs to adjust slowly instead of abrupt changes.


Most store-bought hermit crabs are usually in very bad condition. Most stores don’t provide the right conditions or even food. The chances of such a hermit surviving are very low. Let’s get the second answer to the question – how do hermit crabs die?

Also, check out how to tell if a hermit crab is dead

2. Giving Hermies Chlorinated Tap Water

how do hermit crabs die - giving chlorinated water

Chlorine is a common chemical that is added to municipal water supplies as a disinfectant to kill harmful bacteria, viruses, and other microorganisms that can cause illness. The process of adding chlorine to water is called chlorination.

Chlorine is added to the water in the form of a gas, liquid, or solid. While chlorinated water is safe for humans, it’s toxic to hermit crabs.

Hermit crabs require dechlorinated water for drinking, bathing, and soaking in their shells. You can dechlorinate tap water by letting it sit for 24 hours before using it, or by using a water conditioner specifically designed for removing chlorine from water.

How does letting water sit for 24 hours remove chlorine content?

When water is allowed to sit for 24 hours, the chlorine naturally evaporates from the water.

Chlorine is a volatile compound, which means it readily turns into a gas when exposed to the air. As the water sits, the chlorine molecules will rise to the surface of the water and dissipate into the air. This process is called off-gassing.

It also happens when you expose water to sunlight. After 24 hours, the amount of chlorine in the water will be significantly reduced, making it safe for hermit crabs and other aquatic animals. It’s important to note that this process does not remove other impurities and contaminants from the water.

How to treat hermit crabs’ water

1. Using a water conditioner: There are water conditioners available that are specifically designed to remove chlorine from tap water. These conditioners neutralize the chlorine molecules, making them harmless to aquatic life.

The best water conditioners include

  1. Seachem Prime Fresh and Saltwater Conditioner
  2. Oceanic 81050 Natural Sea Salt Mix
  3. Red Sea Salt Mix for Aquariums

2. Activated carbon filtration: Activated carbon filters can be used to remove chlorine and other impurities from water. These filters work by adsorbing (not absorbing) chlorine and other chemicals onto the surface of the carbon.

3. Reverse osmosis filtration: Reverse osmosis filtration is a process that uses a membrane to remove impurities from water, including chlorine. This method is effective, but it can be expensive.

4. Boiling water: Boiling water will cause chlorine to evaporate. This method is simple and effective, but it may not be practical for large amounts of water.

5. Ultraviolet (UV) light: UV light can be used to disinfect water, including chlorine. This method is effective, but it requires a UV filtration unit and electricity.

It is important to note that before using any dechlorination method, it is best to consult with a veterinarian or other expert in hermit crab care, to ensure that the method you choose is safe and appropriate for your hermit crabs.

Water Solution

Instead of the extra work of dechlorinating water, get two gallons of distilled water. Use one bottle as fresh water and mix the other bottle with sea salts. On the next answer to the question – why are my hermit crabs dying?

3. Bullying or Shell Fights

Hermit crabs are territorial animals and may bully each other to establish dominance and claim a desirable shell or area within their habitat. Also because of food.  This behavior can include pushing, shoving, and biting.

This bullying can lead to injury or death, especially if the hermit crab is forced out of its shell. Additionally, a hermit crab cannot live long without a shell. 

So, if your hermit crab died suddenly, this is a possible cause.

Why Do Hermit Crabs Fight Each Other?

Hermit crabs can attack each other for a variety of reasons, such as competition for resources like desirable shells or a specific area within their habitat.

Additionally, if a hermit crab feels threatened, it may attack in self-defense. Hermit crabs may also attack if they are overcrowded, stressed, or if there is a lack of resources or space. Hormonal changes, such as during the breeding season, can also cause increased aggression among hermit crabs.

  • Shell fights
  • Stress when the conditions in the habitat are not favorable
  • Males fighting for a mate
  • Overstimulation from noise
  • When a hermit crab is surface molting

4. Mold and mildew

The warm and humid conditions encourage the growth of mold, which is why it’s recommended to always watch out for mold growth and remove it instantly. If you are not careful, your hermit crabs will keep on dying.

A large growth of mold and mildew can potentially be harmful to hermit crabs and you. Mold and mildew can also affect the overall environment of the terrarium by reducing air quality and potentially making the habitat uninhabitable for the hermit crabs.

Causes of mold in a hermit crab tank include

  • low humidity levels. Should be above 70%
  • old food lying around
  • poop lying around
  • putting the wooden climbing structure in contact with the water
  • Not mold-proofing wood, ropes, and other moldable structures before putting them in the tank.
  • Lack of proper airflow in the tank (consider a small fan)
  • use or reptile sand
  • keep all moldable items near the heat source

5. Drowning

Do you know that hermit crabs can drown? 

However, only if there is no escape route.

Well, most people often confuse them to be aquatic and they end up providing large or deep pools of water pools without a stable exit.

As much as these critters need both freshwater and saltwater, you need to be considerate about the depth of their water dishes and most importantly ensure there is an exit. Make sure you have followed the right way of making saltwater for hermit crabs.

Remember that land hermit crabs have modified gills and cannot breathe underwater. So, if your crabs have no way out of their pools, they will drown and die.

6. Suffocation

Suffocation is another leading cause of death in hermit crabs. As we’ve seen above, these creatures have modified gills and require high humidity in order to breathe.

Unfortunately, first-time owners are not that great when it comes to maintaining the right humidity in the crabitat.

If the humidity is low, it means your hermit crabs will not breathe as required and will die a slow death. It is hard to know whether your hermit crab is breathing properly, which is why you have to ensure that the humidity levels are just right.

Make sure you use a hygrometer to keep track of the humidity in the tank

7. Unsuccessful Molting

When hermit crabs go into molting, they normally have a 50/50 chance of survival. This process is long and if anything goes wrong, your hermit crab won’t come out of it alive. That’s why it’s key to know how to tell whether a hermit crab is dead or molting.

In most cases, surface molts can lead to death, but sometimes they will survive and go on with life.

Failed molts can lead to deformities in crabs. These deformities can include lost limbs or something of the sort. When this happens, a crab can easily die.

Some crabs won’t even come out of their molts. You will just notice they have been buried for a longer period than normal. Other times you will smell a bad odor coming from their tank. Read how long it takes a hermit crab to molt

There is also the risk of other hermit crabs attacking a newly molted hermit crab

8. Stress

Research shows that hermit crabs are more likely to die of stress as compared to most exotic pets. Stress in these crabs can be brought about by so many things including handling, molting, poor conditions, and overcrowding.

Sometimes these crabs will distress by burying themselves, but if they don’t, they will stop eating and die slowly. Make sure your hermit crab stays happy by improving their tank conditions and providing them with toys to play with, and partners as well.

9. Wrong Husbandry

Hermit crabs will die pretty fast if the conditions in their tanks are not favorable. As you well know, these creatures require plenty of humidity, deep substrate, saltwater, freshwater, and a temperature of 75-85 degrees Fahrenheit during the day and 65-75 degrees Fahrenheit at night.

Failure to provide these requirements will definitely result in sickness and your pet hermits will keep on dying. For instance, if the temperatures get too hot, then your hermit crab will die. Low humidity and lack of water will also lead to death by suffocation.

10. Lack of Shells

I am pretty sure you understand the importance of shells to hermit crabs by now. Shells do not just act as their home, but also offer protection to their delicate abdomens.

So, on the off chance, that your hermit crab gets out of its and fails to find a new one, then it will die. Their abdomens are so soft and can get burnt if not covered by a shell.

Related articles

11. Committing Suicide

This may sound far-fetched but I have seen many hermit crab owners’ situations that appear like the hermit crab want to kill itself. The hermit will sometime willingly move out of the shell only to be found dead outside. The old shell will still be unoccupied hence you cannot say that was a shell fight.

I saw another owners say their hermit crab was always laying upside down. Even after helping the hermie, it will flip back to the other position. Then after a few days, the crab will be found dead. These situations are closely related to stress such as post-purchase stress or an uninhabitable tank.

12. Iodine from table salt

The table salt that you buy and use at home contains human-made iodine. Iodized salt is a salt containing potassium iodide and sodium iodide. While iodized salt helps to prevent iodine deficiency in humans, it can be harmful to hermit crabs.

That’s why is not recommended to use table salt to make salt water.

This is because sodium produces chlorine gas in water, which can cause blisters and burns on the hermit’s gills. Prolonged exposure to such water can result in death.

Ignorance and neglect

13. Ethoxyquin

Ethoxyquin is a preservative that is commonly found in some hermit crab’s food. While many pet food brands claim that Ethoxyquin is harmless to hermit crabs, there is a lot of contradicting information about its safety. To be on the safe side, I don’t recommend foods with Ethoxyquin to minimize the accumulation risks.

14. Old age

There is very little you can do here, but hermit crabs also die of old age. For instance, Jonathan Livingston Crab died at the age of 44. Carol Ann Ormes reported she owned this pet for more than four decades, which is way higher than 30 years, which is the average lifespan of most hermit crabs

15. Attack by other pets such as wrasse

If your hermit crabs are sharing a tank with other hermit crabs such as wrasse, they can kill them. I have seen numerous reports of deaths caused by wrasse attacks

16. Loneliness

Yes, loneliness can kill stress a hermit crab eventually leading to death. Hermit crabs are social animals and it’s recommended to always have a couple.

Wrapping Up

As you can see, hermit crabs are very delicate creatures and can easily die if you neglect them. So, if you are asking, why do my hermit crabs keep dying, you must be doing something wrong. Luckily, preventing these deaths is doable.

Check out this article on how to keep hermit crabs alive. I am pretty sure you’ll get some tips on how to prevent untimely deaths.

Frequently Asked Questions on Why Did My Hermit Crab Die

What happens when hermit crabs die?

When a hermit crab dies its body becomes rigid and loose, making it very easy to come out of the shell. After a few days, the dead hermie will start decomposing producing a rotten smell.

What are the signs of hermit crabs dying?

A dying hermit crab will portray several uncommon habits such as refusing to get into a shell. Moving around without a shell. Being lethargic. Lying upside down and refusing to stay upright. Hiding without coming out to feed.m

Why did my hermit crab leave its shell and died?

A hermit crab will leave its shell if it’s too big or small for them. This can also happen when the hermit is stressed up. The cause of stress can be an uninhabitable tank. Body irritants such as sand or pest.

What to do with a dead hermit crab?

The first thing to do when you think your hermit crab is dead is to first confirm that it is actually dead. The ideal way is to do a sniff test. If it’s indeed dead, then remove it from the tank and put it somewhere for instance in a Ziploc bag.

The next step is burying it. Here it depends on your personal preference. Most people prefer burying it in a hole in the backyard or garden. The hole should be deep enough to avoid dogs or other animals from digging it up. You can also bury it in the park or forest.

Do hermit crabs die easily?

Yes, if you don’t provide the right environment and food, the hermit crab will die. That’s the reason why so many hermit crabs die as the owners don’t know how to take proper care.


How long should hermit crabs live for?

When the conditions are ideal, hermit crabs can live up to 30 or even 40 years. However, hermit crabs tend to die very fast in captivity because many first-time owners don’t know how to care for them

Can hermit crabs die from being too cold?

Yes, extreme cold temperatures can kill a hermit crab. They start by hiding which looks like hibernation then die. Note, hermit crabs cannot hibernate since they are cold-blooded organisms.

How do you bring a hermit crab back to life?

Unfortunately, there is nothing you can do to revive the hermit crab if it’s dead. The only thing you can do is first confirm it’s dead. The surest way is if there is a rotten smell.

Can hermit crabs die from stress?

Yes, hermit crabs can die from stress. This can be post-purchase stress which comes from the change in the environment. Other causes include a crowded habitat, loneliness, incorrect temperature, and humidity levels.

References for Why Did My Hermit Crab Die











Simon Griffiths

Hi guys, my name is Simon, a fellow pet lover. I love everything about traditional and exotic pets so I am here to help you create a better home for your pets.