hermit crabs aggressive towards each other

Why Do Hermit Crabs Attack Each Other?

Last Updated on: 27th September 2023, 10:49 am

Hermit crabs are social, hierarchical animals that live in large colonies. Of course, they’ll want to replicate this arrangement in captivity, as they usually get along well with each other.

Hermit crabs playfight in several ways, including wrestling or fencing with antennae, pushing, and climbing on each other. Even disputes over shells are usually resolved amicably.

Common reasons for hermit crabs fighting include asserting social dominance, claiming territory, battling for the right to mate, or winning a coveted shell.

A warning sign that two hermit crabs are fighting is the use of chelipeds, especially attempting to sever eye stalks. If you notice these behaviors, the hermit crabs must be separated.

Minimize the risk of hermit crabs attacking each other with a large tank where all hermit crabs have territory, provide a selection of spare shells, and avoid external stimulation.

Are Hermit Crabs Aggressive Towards Each Other?

Hermit crabs have a well-earned reputation as timid, docile animals. You can put several hermit crabs in the same tank because they like each other’s company. 

Despite this, conflict can arise between hermit crabs.

Social hierarchy is vital to hermit crabs, so they may occasionally clash over alpha status. Thankfully, most hermit crabs settle disputes amicably, often through play fighting.

Hermit crabs play fight for recreation in several ways, including:

If hermit crabs are playing, they’ll take turns acting as aggressors. Equally, if a hermit crab is knocked onto its back, it’ll be assisted, or if it hides, the other hermit crab will move away.

What Does it Look Like When Hermit Crabs Are Fighting?

While play fighting is natural for hermit crabs, outright aggression must be identified and stopped. You can determine the difference when chelipeds become involved.

If two hermit crabs actively fight, they’ll start pinching – not just pushing and rocking.

More importantly, the claws will be directed at delicate parts of the anatomy, like the eye stalks. If hermit crabs attempt to sever eyes, the dispute has been escalated.

Listen out for noises. As hermit crabs go about their lives, you may hear a low, regular chirping. Increasingly loud chirps can signify that one hermit crab is distressed or afraid.

why is my hermit crab aggressive?

Can Hermit Crabs Hurt Each Other?

If a hermit crab conflict turns aggressive, injury becomes more likely. Hermit crabs sometimes lose limbs during fights, while others shed legs or lose claws to escape or as a distraction.

Even if hermit crabs choose to shed a limb, it’ll be uncomfortable. Applied Animal Behavior Science stated that hermit crabs feel pain and may shed as the lesser of two bad situations.

Do Hermit Crabs Fight to the Death?

If hermit crabs are left to fight, there’s a risk that one won’t survive. Even if the fight doesn’t end a life, the ongoing stress can have life-ending consequences.

Can Hermit Crabs Avoid Fighting?

Unless both hermit crabs are aggressive, one will likely be less interested in confrontation than the other. The victim of the attack will do what it can to avoid a fight.

Most hermit crabs avoid conflict by hiding in their shell. This sometimes works, as the aggressor may rap and rock the shell for a while, eventually growing bored and moving on.

If a hermit crab is particularly hostile, it may drag the victim out by force.

Why Do Hermit Crabs Fight Each Other?

While stress and unhappiness can explain why a hermit crab grows agitated and cantankerous, there will often be a direct explanation for aggression. Consider if one or more of the following apply:


Hermit crabs are easily stressed in captivity, and prolonged stress affects their behavior. As an owner, you must care for the hermit crabs to provide a stress-free environment.

If the hermit crabs are growing agitated, check for the following:

  • Is the tank at the right temperature? It should be no cooler than 72°F, no hotter than 84°F.
  • Does the tank have a humidity level of 80%?
  • Are the hermit crabs getting enough dietary protein?
  • Do the hermit crabs have sufficient entertainment to avoid boredom?
  • Is the tank clean, and do the hermit crabs have the chance to bathe regularly?

The wrong conditions can make hermit crabs unhappy and confrontational.

Social Hierarchy

No matter how many hermit crabs you keep in a tank, one of them will become the alpha. This is a natural behavior for hermit crabs, who automatically arrange themselves into a social hierarchy.

The advantages of holding alpha status in a hermit crab colony include the first refusal of food and new shells. Typically, the largest hermit crab in a tank will assume this capacity.

After molting, hermit crabs are likeliest to fight for a higher place on the social ladder. When hermit crabs molt, they increase in size and regrow lost limbs. This can embolden a once-submissive hermit crab.

Territorial Disputes

Wild hermit crabs have an entire beach to traverse, so there’s ample territory for everyone. Squeezing many hermit crabs into a 10-gallon tank will inevitably lead to confrontation.

All hermit crabs will burrow under the substrate to sleep and molt, so they’ll want territory. This can be quickly resolved by giving hermit crabs more space.

10 gallons may be large enough for 2-3 hermit crabs, but consider getting a 20-gallon tank if you have more than 5 hermit crabs in your care. Also, add more substrate.

hermit crab fighting behavior

Right to Mate With A Female

Female hermit crabs are unlikely to breed in captivity but still enter season. When fertile, a female releases pheromones that attract males. Male hermit crabs may fight over the right to mate.

Often, the alpha hermit crab will invite the female to breed. She may decline this invitation by hiding in the shell, but the male will still ‘guard’ her.

The female hermit crab will stop releasing pheromones after 3 to 4 days. At this point, the male will cease guarding and become disinterested in pursuing her.

Shell Wars

Hermit crabs will enter conflict over coveted shells. A shell is a hermit crab’s home, providing shelter and safety from external threats. All hermit crabs want the best shell.

If a hermit crab covets the shell of another, it’ll challenge it by rapping upon the vessel. If the incumbent hermit crab agrees to this contest, they’ll indulge in antennae wrestling.

Some hermit crabs can aggressively pursue a shell, including forcefully dragging out the owner.

Providing spare shells minimizes the risk of these encounters.

What To Do If Your Hermit Crabs Are Fighting

If hermit crabs are fighting, they should be separated to avoid ongoing stress.

Don’t leave a hermit crab alone for too long. As social animals, living without company will make a hermit crab unhappy. After a few days, return it to the main tank and observe interactions.

You may notice that the tank dynamics change after a fight. Behavioral Ecology and Sociobiology said that hermit crabs base their interactions on previous experiences, recalling specific individuals.

Genuine conflict between hermit crabs is uncommon, but it happens. Learn the difference between two hermit crabs playing and fighting, separating the ones who don’t get along.