Despite their name, hermit crabs are social animals that dislike being alone.
Hermit crabs live in large colonies in the wild, frequently numbering 100 members or more. The name ‘hermit crab’ refers to the fact that only one animal lives in a single shell.
Hermit crabs live together for various reasons, primarily revolving around protection.
As small animals, hermit crabs are at the bottom of the food chain and seek safety in numbers. More hermit crabs in a colony also mean more shells to trade.
Cohabiting hermit crabs don’t need to be the same species, but terrestrial hermit crabs can’t live with marine hermit crabs because they have different anatomy and environmental needs.
How To Introduce New Hermit Crabs
Introducing new hermit crabs into a colony involves following these steps:
1/ Compatibility Between Hermit Crabs
Most terrestrial hermit crabs can contentedly live together, but marine hermit crabs often have unique aquarium water requirements.
Don’t be too concerned about size when mixing different hermit crab species.
Larger hermit crabs can reside with smaller conspecifics if the discrepancy isn’t too substantial. These size differences will also prevent fights over shells.
If you’re bringing a unique species of hermit crab into a colony, such as a lone Ecuadorian, into a tank of Purple Pinchers, consider waiting until the new arrival has 1 or more same-species companions.
2/ Habitat Suitability
Start by ensuring the aquarium is large enough to accommodate new arrivals. As a rule, a habitat should have at least 5 gallons of space for each pair of hermit crabs.
If you have a 10-gallon tank, 4-5 hermit crabs will be fine. Before adding another 2 or more hermit crabs to the colony, upgrade to a 15-20 gallon tank.
Consider how you can accommodate the needs of the tank’s residents.
When adding larger hermit crabs than the incumbents, you’ll need to apply deeper substrate to ensure they can dig and burrow when needed.
Add entertainment (small rocks, climbing frames, etc.) and hiding places to the tank.
Ensure that all the hermit crabs have somewhere to destress and relax if they want some alone time, and there are enough places for everyone to climb, explore, and interact with their environment.
3/ Allow Time to Destress
All pet hermit crabs start life in the wild and are captured from their natural habitat before being prepared for sale. This is a stressful experience for hermit crabs, meaning they’ll experience post-purchase syndrome (PPS) and must be left alone.
Post-purchase syndrome is a period of intense stress for hermit crabs as they come to terms with their new surroundings. Prepare an isolation tank for your new pet hermit crabs and put them inside, ensuring the habitat offers sufficient heat, humidity, and substrate.
Hermit crabs will burrow under the sand until they’re ready. This could take several weeks, and you mustn’t disturb the hermit crabs throughout the process.
New hermit crabs may also molt their exoskeleton during this period of destressing. Try to wait until this happens before you remove them from their isolation tank, as a new, sturdy exoskeleton will help the hermit crabs thrive in an unfamiliar colony.
4/ Clean the Main Tank
When new hermit crabs are ready to meet their new tankmates, clean the master tank.
This means you’ll need a third tank in the short term, as the incumbent hermit crabs will need somewhere to live while you’re doing so.
Cleaning the primary hermit crab tank is about neutralizing the habitat for all inhabitants. The resident hermit crabs are likelier to accept new arrivals if they don’t feel they’re losing territory.
Cleaning the tank removes existing scents associated with social hierarchy. You can also change the decor so the existing hermit crabs feel like they’re in a new habitat, giving them a unique area to explore.
Place some items from the new hermit crabs’ isolation tank with the established hermit crabs and some pre-used decorations in the isolation tank. This will help all the hermit crabs acclimatize to the scent of each other, reducing the risk of aggression upon meeting.
5/ Add all Hermit Crabs to the Master Tank
Once the tank is clean, add all the hermit crabs, old and new. The ideal time to do this is dusk, just as the hermit crabs wake up. Place food in the tank ahead of time, then move them across.
The hermit crabs will initially be distracted by the scent of food, as they likely woke up hungry. This desire to eat will supersede any concern about new arrivals in a habitat.
After eating, the hermit crabs will be energized and seek exercise. They’ll have plenty to explore as you’ve moved everything around. So, the hermit crabs are less likely to make a beeline for each other.
6/ Monitor The Interaction Between Hermit Crabs
Hermit crabs encounter each other and notice that new arrivals are now residing in their tank. You’ll need to observe how these interactions unfold, ensuring they coexist peacefully.
Do Hermit Crabs Fight?
Hermit crabs get along well, but conflict can arise. Common reasons for fighting include:
| Social dominance | Hermit crabs abide by a strict social hierarchy. As per Ethology, hermit crabs respect their place in the pecking order, but new arrivals may challenge this status. |
| Mating | Hermit crabs rarely breed in captivity, but females still enter season and release pheromones that attract male attention. Then, male hermit crabs may battle for the right to breed with a female. |
| New shells | As hermit crabs aren’t born with shells, they sometimes fight over what’s considered the best shelter. Behavior explains how these disputes can be settled amicably with all parties satisfied by the outcome, but the challenge can grow hostile. |
Often, hermit crabs wrestle with their antennae to challenge for dominance and engage in pushing contents as tests of strength, which is a form of play.
How Do I Know if My Hermit Crabs Get Along?
Hermit crabs may physically interact in a manner that looks like fighting. If hermit crabs’ claws remain inactive during these conflicts, let them settle their differences.
If they’re attempting to pinch with claws, especially looking to sever eye stalks, they may be looking to kill each other. If so, the hermit crabs must be separated into an isolation tank.
Be careful when separating hermit crabs because you can get pinched. Place one of the hermit crabs in an isolation tank and let it cool off. Reintroduce the hermit crab to the tank later.
If you slowly introduce new hermit crabs to each other, they should get along okay. Hermit crabs relish the company of their species and enjoy living in large colonies.
