Hermit crabs are one of our most popular pets, and Birdsville, Sydney’s small animal and reptile specialist, regularly has them in stock. Kept in the right conditions they’re surprisingly active, but they’re also one of the less forgiving invertebrates to get wrong: correct heat and humidity aren’t optional extras, they’re the difference between a thriving crab and a dead one. This pet Hermit Crab care guide sets out everything you need for the Sydney climate so yours stays healthy from day one.

Quick Facts

Scientific name: Coenobita variabilis
Also known as: Australian Land Hermit Crab, Aussie Hermit Crab
Adult size: carapace up to around 4cm, living in a shell roughly golf ball sized or larger
Lifespan: up to 15 years
Diet: omnivore, pellets plus fresh fruit and vegetables
Enclosure minimum: 38 litres per crab
Temperature: 26 to 32°C, never let it drop below 20°C
Licence requirement: none for native Australian species
Experience level: beginner to intermediate, humidity and heat need daily attention

On This Page: Hermit Crabs as Pets, Essential Supplies, Housing, Environment, Diet & Feeding, Providing Water, Behaviour & Handling, Common Health Issues, Parasite Control, Health, Hygiene & Safety, Toxic & Dangerous Hazards, Sexing, Record Keeping, Holiday Care, Transportation, Compatibility with Other Animals, Frequently Asked Questions

Hermit Crabs as Pets

Hermit crabs are crustaceans native to northern Australia, found along the coasts of northern Western Australia, the Northern Territory and northern Queensland. The hermit crabs at Birdsville are native Australian stock, shipped in from the Northern Territory. They’re ectothermic, meaning cold blooded, so outside a tropical climate they rely entirely on you for heat. They’re also gill breathers: even on land, those gills need constant moisture to work, which is why humidity matters as much as temperature. Hermit crabs live in salvaged gastropod shells instead of growing a shell of their own, moving into a larger one every time they outgrow the current one, and they’re strictly nocturnal, coming out to feed after dark. They can’t be bred in captivity, since their larvae need the ocean to develop, so every crab in the pet trade is farmed or collected from the wild, not raised at home.

Tank or terrarium: at least 38 litres per crab, with a secure, ideally glass or acrylic lid. Hermit crabs are strong climbers and will escape through any gap they can find.
Thermometer and hygrometer: essential for tracking both temperature and humidity, not optional extras.
Heating: a heat mat, heat globe or heat coil, placed to one side so the crab can move toward or away from the heat to regulate itself.
Two water bowls: one for fresh drinking water, one for marine salt water for bathing, deep enough to submerge in but shallow enough to climb back out of.
Food bowl: kept stocked at all times.
Hermit crab safe food: a nutritious pellet diet formulated for hermit crabs, not fish food.
Water conditioner: for both the fresh and salt water bowls, to remove chlorine and chloramine.
Marine salt or salt water conditioner: for mixing the bathing water.
Hermit crab safe enclosure cleaner: a product like Hermit Clean breaks down waste and odour without harsh chemicals.
Substrate: coco peat, sand, marine aquarium rock sand, gravel, or a sand and gravel mix, all suitable for lining the enclosure.
Spare shells: at least two spare shells per crab, only slightly larger than their current one, to stop them fighting over shells and to have options ready for their next moult.
Decorations and climbing enrichment: driftwood, rocks, coral, mangrove root and similar, which help crabs feel secure as well as look good.
Sea sponges: placed in the water bowls, they help disperse humidity and give crabs a foothold to climb back out.

You’ll find every item on this list, and plenty more besides, in store at Birdsville, ready to see and handle before you buy.

What You May Consider: positioning the enclosure near a window for natural light, which helps keep your hermit crabs’ circadian rhythm in check, and a spare humidity mister for busy weeks when daily spraying isn’t practical.

Housing

A tank or terrarium of at least 38 litres per crab gives enough room to move, climb and bury for a moult, with a secure lid to stop escapes. As you add more crabs, or as an individual grows, increase the enclosure size and shell options accordingly. A cramped tank is one of the most common causes of shell fighting.

Setting Up Your Hermit Crab Tank

1. Line the base with your chosen substrate, deep enough for burrowing, at least 4cm thick if you’re running a heat mat underneath.
2. Add rocks, driftwood, coral and other safe climbing decor to enrich the space and give crabs somewhere to explore and hide.
3. Leave a clear area for crabs to move around freely, alongside the hiding spots.
4. Position the heat source to one side instead of under the whole tank, so crabs can move toward or away from it to find their ideal temperature.
5. Place the two water bowls and one food bowl somewhere easily accessible.
6. Add water conditioner and marine salt to the water bowls, keeping fresh and salt water separate, and drop a sea sponge into each.

Keep the tank off carpet. Loose fibres can snag delicate legs, and carpet cleaning products are a chemical hazard for an animal this sensitive.

Environment

Hermit crabs need a stable 26 to 32°C, and prolonged cold below 20°C can be fatal, so a reliable heat source is essential outside the tropics. Humidity needs to stay between 70 and 85% to keep their gills working properly; below that, they can genuinely suffocate. An automatic mister is the easiest way to hold humidity steady, though frequent hand spraying works too if you’re consistent about it. A little natural light from a nearby window helps keep their day and night cycle on track, and beyond that, no dedicated lighting setup is needed.

Diet & Feeding

Hermit crabs are omnivores, and in the wild they’ll eat almost any scraps they find, so a good pellet diet forms the core of their nutrition alongside fresh fruit and vegetables such as kale, broccoli, apple and banana. Keep a food bowl stocked at all times, and offer fresh produce overnight, removing anything uneaten by morning so it doesn’t spoil or attract fruit flies. Always have there hermit crab food available at all times, an all you can eat buffet. Never feed fish food or other foods containing copper, which is toxic to hermit crabs, and always clear away leftover scraps promptly since rotting food can make them sick.

Providing Water to Your Hermit Crabs

Hermit crabs need two separate bowls, one with fresh drinking water and one with marine salt water for bathing and minerals. Both should be deep enough to submerge in fully but shallow enough, or fitted with a sponge, for the crab to climb back out without drowning. Add water conditioner to both bowls to remove chlorine and chloramine, and change the water daily.

Behaviour & Handling

Hermit crabs are nocturnal and will mostly stay hidden or inactive during the day, only coming out to feed and explore after dark. Every crab has its own personality: some settle quickly and tolerate handling well, while shyer ones take longer but usually come around with regular, gentle handling. Around moulting time a crab will bury itself and may stay out of sight for a week or more while its new shell begins to harden; avoid handling for roughly three to four weeks after a moult to give the exoskeleton time to fully set.

Common Health Issues

Dehydration and Low Humidity Stress

Hermit crab gills stop working properly below the required humidity range, which can lead to laboured movement or worse. Keep humidity between 70 and 85% at all times, checked with a hygrometer rather than guesswork.

Shell Stress

Without enough correctly sized spare shells, crabs will fight each other for the ones available. Always keep at least two spares per crab on hand, sized just above their current shell.

Moulting Complications

A crab disturbed or handled too soon after moulting can suffer serious injury before its new exoskeleton hardens. Leave a freshly moulted crab undisturbed with food and water nearby for three to four weeks.

Lost Limbs

Crabs occasionally lose a limb if it gets caught in decor, or if another crab tries to pull them from their shell. Limbs regrow gradually with each subsequent moult.

Parasite Control

New hermit crabs should be kept in their own enclosure, separate from any existing group, for 4 to 6 weeks before mixing them together. It’s the same quarantine window Birdsville uses for every new animal, and it gives you time to confirm your new arrival is settled and eating properly before it joins the rest of the group.

Health, Hygiene & Safety

Every 24 Hours

Check and top up food, give the tank a spray with non-chlorinated water, and make sure both the fresh and salt water bowls are full.

Every Week

Spot clean the enclosure and wash out both water bowls, on top of the daily water changes above.

Once a Month

Refresh or clean the substrate, and use a hermit crab safe cleaner if the tank starts to develop an odour. Add water conditioner to the final rinse water, since tap water chlorine damages hermit crab gills.

Toxic & Dangerous Hazards

Copper is toxic to hermit crabs and turns up in most standard fish food, so stick to a purpose-made hermit crab diet, not anything from the fish aisle. Untreated tap water contains chlorine and chloramine, both harmful to their gills, so always use a water conditioner. Household sprays, air fresheners and scented candles used anywhere near the tank can affect a creature this small, so keep the enclosure well clear of them. Never let a crab roam loose on carpet either, where fibres can snag their legs and any cleaning residue in the pile is a genuine hazard.

Sexing

Reliably sexing a hermit crab isn’t something most keepers can do by eye. Since they can’t be bred in captivity, sex isn’t something Birdsville team members would be able to do.

Keep a simple log of feeding, moult dates, shell changes and any temperature or humidity checks, along with anything unusual like a lost limb. Given a lifespan that can stretch to 15 years, a log makes it much easier to track their health over time instead of relying on memory.

Hermit crabs are less forgiving of a missed routine than most pets, since humidity has to stay in range every single day. A short trip away is fine as long as the tank is fully topped up and misted before you leave, ideally with an automatic mister running. For anything longer than a couple of days, arrange for someone reliable to check food, water and humidity daily, with clear written instructions on the correct ranges.

Use a secure, ventilated container with a little moist substrate or damp paper towel inside for longer trips. Keep the journey short, avoid temperature extremes, and never leave the container unattended in a parked vehicle.

Compatibility with Other Animals

Hermit crabs are gregarious and generally do well kept together in a group, provided there are enough correctly sized spare shells to prevent fighting. Keep them away from fish, reptiles or other animals that might see them as prey, and quarantine any new crab before introducing it to an existing group.

Why is my hermit crab buried in the substrate and not moving?

This is almost always a moult, not a problem. Hermit crabs bury themselves to moult safely and can stay hidden for a week or more while their new exoskeleton starts to harden. Leave them undisturbed with food and water nearby rather than digging them up to check.

How often do hermit crabs moult?

Most hermit crabs moult around twice a year, shedding their old exoskeleton so they can grow into a new one. They typically eat the discarded skin afterwards, since it’s rich in calcium, so leave it in the tank instead of cleaning it out if you happen to spot it.

Can I keep hermit crabs together?

Yes. Hermit crabs are naturally gregarious and generally do well in groups, as long as there are enough correctly sized spare shells for everyone, at least two per crab. Without enough spares on hand, crabs will compete and sometimes fight over whichever shells are available.

How long do pet hermit crabs live?

With correct heat, humidity and diet, hermit crabs can live up to 15 years, an unusually long lifespan for an invertebrate this size. That makes daily humidity and temperature checks a genuine long-term commitment rather than a one-off setup job you can forget about.

What size tank does a hermit crab need?

Hermit crabs need at least 38 litres of tank space each, with a secure, tight-fitting lid since they’re strong, determined climbers that will find any gap going. Increase the size as you add more crabs or as an individual grows, since a cramped tank makes shell fighting far more likely.

Is a hermit crab a good first pet?

Hermit crabs can be, but they’re less forgiving than many invertebrates: humidity and temperature need daily attention, not occasional checking. Go in ready to monitor a hygrometer and thermometer regularly, and a hermit crab makes a genuinely fascinating, long-lived display pet.

Visit Us

Drop into Birdsville at 684 Botany Road, Alexandria to see our hermit crabs and pick up everything you need in one visit. Our tarantula, scorpion and stick insect care guides cover some of our other easy-care invertebrates, worth a browse if you’re still deciding what to add to the collection.