Do Hermit Crabs Smell Bad?

For those considering getting a hermit crab pet, or new to having them as pets, the question “do hermit crabs smell bad” is a common one. Pets like dogs, cats, chickens and birds can all smell bad at times, due to fur and feathers, dander, poop, diet and more. And because of this, people sometimes choose hermit crabs as pets because there aren’t the same needs for regular baths and overall maintenance.

Hermit crabs do not have an odor

Hermit crabs have no odor, so they can’t smell bad themselves (at least any smell that’s detectable to us). Perhaps they have their own distinct scents, like humans do, which differentiate them from each other. But there is no detectable odor, smell or scent from a hermit crab to a human .

They have an exoskeleton that doesn’t absorb or excrete any odors or need outside help to wash or clean them. They bathe to drink but also to help absorb water for storing in their shells (the reason they need water dishes deep enough to submerge).

And they go through a molting process periodically, shedding their older exoskeleton and growing a new one.

There CAN be bad smells in a hermit crab habitat

There are three main causes of bad smells in a hermit crab habitat:

Stagnant, foul water
Rotting food
Dead hermit crabs

While hermit crabs don’t produce any particular odor themselves, an unclean habitat can produce plenty of bad smells.

Stagnant, foul water

It’s very important to change the water daily and weekly, as needed (I wrote a blog with tips and information on hermit crab water you can find here). Most especially if you use smaller water dishes with no aeration, the water can become foul quickly. Hermit crabs will inevitably climb in, poop in the water, they may drag food in too and the water can get gross quick.

Some things to consider: use a larger habitat with room for water pools (larger, deeper than a regular dish) where you can add a submersible mini water filter (see the one we use in our freshwater water pool here). If you use small water dishes that are at least 1.5″ deep, you can add an air stone which helps aerate the water (helps keep it healthier). See more on how hermit crabs love moving water and options for your hermit crab habitat here.

Rotting food

Food (most especially fresh, moist foods) should be removed within 24 hours. These moist, fresh foods start rotting right away even when you can’t see it. It will start attracted unwanted pests like fruit flies (gross!). And when left too long, it can cause foul odors in your hermit crab habitat. The smaller the habitat, the larger the smell.

Strawberries, as an example, should be removed within 12-24 hours. They rot very quickly. Tomatoes can also start rotting quickly. Foods that are full of moisture need to be removed within a day, but they are still very important to feed your hermit crabs.

Dead hermit crabs

Most often, in a healthy hermit crab habitat, hermit crabs “disappear”. They die while molting, buried under the surface level so they aren’t visible.

And when they die while they are buried, they will either get eaten by other hermit crabs (their exoskeleton is calcium rich and nutritious, the circle of life!). Or they will decompose quickly and one day you’ll find a deeply buried empty shell. There is NO SMELL when a hermit crab dies while buried. Chances are you won’t ever know for sure that it happened.

Any dead hermit crabs that are visible and above the substrate should be removed right away. Visible dead hermit crabs can cause foul smells in your hermit crab habitat (and could be devastating to their hermit crab tank buddies?).

The smaller the habitat, the more likely it could smell bad at some point

One more note on hermit crab habitats and avoiding smells: generally, the larger the hermit crab habitat (including size of water dishes) the easier it is to keep clean and well maintained. The smaller the hermit crab habitat, the more frequently you have to clean everything. Information on setting up a hermit crab tank here.

Looking for ideas on creating a unique, custom, fun hermit crab habitat from a piece of Ikea furniture? See our Ikea Detolf Hermit Crab Habitat Hack here and our super big Ikea Milsbo Hermit Crab Habitat Hack here.

In conclusion, hermit crabs are relatively low maintenance and can make an ideal pet. They probably won’t need landlord or association approval, they can be left alone while you go on vacation (see tips on leaving hermit crabs alone while you’re away here), and they are very interesting and unique little creatures to enjoy. As long as the habitat remains clean, hermit crabs and their habitat won’t have any bad smells to be concerned about.