Do Hermit Crabs Smell Bad

Do Hermit Crabs Smell Bad ? Explore Top 5 Reasons

Owning a pet is an affectionate and adorable experience. This experience also comes with the challenge of dealing with unpleasant odors associated with some pets. Everyone wants their house to smell fresh and pleasant. Regarding this, crab lovers must be wondering: Do hermit crabs smell bad?

Hermit crabs do have a distinct aroma that most crustaceans exhibit. Under normal circumstances, hermit crabs do not emit an odor that is offensive to the nose. If your hermit crab is giving off an unbearably bad odor, there must be some underlying issue. In this case, look at the health of your crab and the conditions of the tank. 

Hermit crabs are the favorite pets of crab lovers because they are low-maintenance. These unique crabs are known for their fascinating and colorful shells.

However, the crustacean-like smell of hermit crabs can be a problem for some people. So, in this article, we will discuss the reasons that cause this foul odor and all the solutions for it. 

Why Does My Hermit Crab Smell Bad?

Usually, hermit crabs give off a distinct marine-life aroma that is not a problem for most people.

It is unusual for hermit crabs to smell extremely unpleasant without a reason. The following can be possible reasons for your hermit crab smelling bad. Examine the following factors to figure out the issue, and take the required actions.

  1. Substrate: The substrate you are using as sand in your tank can also be the cause of stink. There are some types of substrate that stink when they get wet. Therefore, always opt for a high-quality, organic substrate for your tank. 
  1. Build up of Decaying Food: Hermit crabs only consume small portions of the food they are given. The excessive food will start to decay and give off unpleasant odor. Hermit crabs also tend to bury leftover food. When this food breaks down, the tank starts stinking. 
  1. Accumulation of Waste: Hermit crabs store their solid excretions in their shell until they feel the need to clean it. They empty out their shells by dropping the stored excrements on the substrate. If the tank is not cleaned regularly, the pop will build up and produce foul odor. 
  1. Stressful Condition: Another reason that can cause your hermit crab to smell bad is stress. Hermit crabs release a special type of hormone called pheromones when they feel distressed. These pheromones cause a foul smell that helps hermit crabs put off predators. Hermit crabs can also lose limbs in stressed conditions. The decay of that limb will further add to the unpleasant odor. 
  1. Overheating: Hermit crabs require moderate temperature conditions to thrive in captivity. An excessive increase in temperature can cause them to dry out. This will in turn induce stress in your pet, and they will start releasing smelly pheromones. It is important to maintain the optimal temperature and humidity in the tank.

Do Hermit Crabs Smell Bad?

Naturally, hermit crabs do not smell bad. They have the usual crustacean-like smell that is bearable for most people.

However, they do give off an intolerable odor when the living conditions are not optimal. There are various possible factors that can cause hermit crabs to smell bad. 

Hermit crabs release a foul odor when they are stressed out. This stress can be induced by various different factors. A healthy hermit crab does not emit a bad odor, other than its natural scent. 

The inappropriate conditions of the tank also evoke the problem of an unpleasant odor. When the maintenance of the tank is neglected, the optimal conditions for the hermit crabs start to deviate.

Therefore, whenever you detect an offensive scent from the tank of your tiny pet, examine the conditions of the tank.

Related article: Why Do Hermit Crabs Burrow ?

Do Hermit Crabs Smell Fishy?

Hermit crabs do not inherently smell bad. However, there are certain situations in which hermit crabs give off an offensive odor.

Hermit crabs smell fishy when they are dead. When a hermit crab dies, its body starts decomposing. 

The process of decomposition involves various enzymes and chemicals. These substances cause the fishy smell when a hermit crab expires. 

Whenever you detect a fishy odor from your hermit crab, start examining its activity. If your crab has become completely inactive, it means it has died.

It is recommended to remove a dead hermit crab immediately to prevent the intolerable fishy smell from spreading in the house.

Do Hermit Crabs Smell When Molting?

Yes, hermit crabs emit a distinct and unpleasant smell during the process of molting. Molting is essential for hermit crabs, as it allows them to develop a bigger exoskeleton. 

When a hermit crab undergoes molting, it sheds its exoskeleton. The tissue of the shedded exoskeleton starts decaying and emitting a noxious smell.

Moreover, the hermit crab itself releases pheromones during molting to protect itself from predation. 

Molting is a natural process that every hermit crab goes through frequently. Therefore, owners have to tolerate the bad smell during the molting phase of their crabby pets. 

Do Hermit Crabs Smell When They Die?

Yes, when a hermit crab dies, it releases an extremely unpleasant smell. The dead body starts to rot due to bacterial and enzymatic activity. This leads to the emanation of malodorous scents. 

The nasty fish-like smell announces that a crab has perished in your tank. This scent tends to excite and attract other hermit crabs to the site of their demise. Other hermit crabs not only feed on their dead tank mate but also try to claim the newly available shell.

It is not recommended to let other hermit crabs feed off the dead body because it may have died due to a disease or pathogen that can potentially transfer to the healthy ones.

Related article: How Long Can Hermit Crabs Stay Underwater? Exploring Their Aquatic Abilities

Do Hermit Crabs Have a Good Sense of Smell?

Hermit crabs have developed a good sense of smell. They have the ability to detect and differentiate a range of scents.  They utilize their strong sense of smell for food hunting, mate detection, and identification of predators. 

In the context of evolution, hermit crabs are primitive animals. They do not have a nose for detecting scents. Instead, they have thousands of olfactory sensors embedded in their antennae. These sensors perceive different chemical molecules suspended in the air.

How to Keep Hermit Crabs From Smelling?

Having your favorite pet smell like rotting fish is really annoying. But we can also not blame our little crabs for stinking. It is mostly because of our own neglect that they start giving off offensive odors. Here are some steps that you can take to keep your hermit crab from smelling:

  • Remove the poop and droppings of hermit crabs from the tank on a daily basis. 
  • Immediately discard the leftover food, as hermit crabs tend to bury it in the sand. 
  • Clean the walls of the tank to remove the residues of urine and feces.
  • Change the substrate of the tank often. 
  • Place the tank at a place that has good airflow and sunlight coming in. 
  • Clean and sanitize the decor of the tank, as these pieces can also carry a scent.  


 Should I Spray Air Freshener In the Tank?

No, air freshener should never be sprayed in the tank. Air fresheners contain strong chemicals that can be extremely toxic for hermit crabs. These toxic chemicals can lead the crabs to death. 

What is Causing My Hermit Crab To Stress?

Hermit crabs stress out when they feel vulnerable in their habitat. Lack of hiding places, inappropriate tank conditions, overstimulation, unhygienic surroundings, predators, and loneliness cause hermit crabs to stress.

How to Treat Overheating of Hermit Crab?

When a hermit crab overheats, it can stress out. You can place water pools in the tank. Hermit crabs will take a bath on the water to cool off if they feel overheated.

Does Any Food Also Cause Hermit Crabs To Smell?

Yes, there are certain foods that can cause hermit crabs to smell bad. This mostly includes commercial and processed foods. These foods contain preservatives and additives that are harmful for the crabs. 

Are There Any Odor-Neutralizing Food?

No, there is no odor-neutralizing food available for the hermit crabs. Stinking is a natural process and should be treated in natural ways. 


Hermit crabs are low-maintenance pets as they do not require lots of attention. However, their stink can be a problem for some people. Hermit crabs have a natural crustacean-like smell attached to them. But they can emit a much more intolerable scent when their surroundings are not suitable.  

The happier and healthier a crab is, the less offensive its odor will be. The inappropriate tank conditions also cause stinking issues. Therefore, if you take proper care of the crab and its environment, there will be no bad smell.