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A Complete Beginners Guide To Owning Australian Hermit Crabs

Welcome to what I like to call the "Crab Cult". Why? Because soon you will be obsessed!! Hermit Crab owning has come a long way in the past 20 years and we have learnt so much about the proper care of our little friends. Unfortunately, the Hermit Crab industry has not grown much in their education of proper husbandry. But no need to worry, because we as a community have!


Below we will run through a complete beginners guide to owning Hermit Crabs and soon enough, you will be a confident owner giving your clan the best possible life in captivity.


The Australian Land Hermit Crab (Coenobita Variabilis)

In Australia we have 1 land hermit crab species that is captive. The Coenobita Variabilis. A few years back you could purchase Strawberry Hermit Crabs (Coenobita Perlatus) however they are no longer available for purchase in Australia. Meaning most owners will have the Coenobita Variabilis species in their tanks now.


Our species require a different care to that of their overseas relatives. This is where a lot of new owners get confused. Often following advice from Google, US based hermit crab Facebook groups or YouTube. Always make sure you are checking that the advice you read is based on our Australian species. All information covered in our blogs is based on Australian Hermit Crabs.


Quick Facts

  • Hermit Crabs can live for up to 15 years in captivity if cared for correctly, sometimes even longer!

  • Australian land hermit crabs (Variabillis) vary in color from light beige and grey through to dark browns and reds.

  • Hermit Crabs must shed their outer exoskeleton in order to grow. They do this by moulting.

  • They are Omnivores, meaning they eat both plant matter and animal proteins. They enjoy a diet of fruits, vegetables, plant matter, grains, meats, seafood etc.

  • Despite their name, Hermit Crabs are very socialable and should be kept with other hermit crabs as they can get lonely.


Basic Care Requirements

Below are the basic requirements you will need to fulfil in order to keep your hermit crabs alive and thriving.


  • Glass tank with glass lid - minimum 38L space PER crab

  • Deep substrate - minimum 6" (15cm) deep

  • 2 x deep pools with entry/exit access - marine salt & fresh water

  • High quality Marine Salt

  • Seachem Prime Water Conditioner

  • Thermometer/Hygrometer - for checking temperature/humidity readings

  • Heat source - heat mats or heat cords only

  • 6 x spare natural shells PER crab - avoid painted shells!

  • Food Bowl

  • High quality handmade food mixes - from an Australian supplier

  • Hides - a safe and dark place for them to hide

  • Enrichment - activities, things to climb, wheels, hammocks, nets etc.

  • Light source - 12 hours on, 12 hours off - aquarium light

Tank

Glass fish tanks with a lid work best, secondhand tanks are the place to be! Relatively cheap and they get the job done. You must provide at least 38L of space PER crab to avoid overcrowding which can lead to aggression and death.

Not sure how to calculate your tanks litres? Check out this website below, simply measure your tank LENGTH, WIDTH AND HEIGHT and add the measurements into the site to get your litres!


Substrate

Setting up your substrate correctly from the beginning will not only save you SO much time and back ache, but also saves you money! Substrate should be made up of simple Play Sand and Coir Peat. Both available at Bunnings and most hardware/gardening stores. Our Australian crabs prefer a ratio of 8:1, 8 parts of play sand to 1 part of damp coir peat. This not only leaves your substrate with the correct sandcastle consistency, but also helps aid in humidity and keeping the sub moist enough for successful moulting. DONT get confused with our US cousins, they will mix their substrate at a 5:1 ratio. We NEED an 8:1 ratio. Your substrate will also need to be a minimum of 6" (15cm) deep to ensure plenty of room for safe moulting.


Play sand and damp coir peat should be completely mixed together until there are no large chunks of coir peat left. They DO NOT need a beach area with sand and a forest area with coir peat. JUST SAND/COIR PEAT MIXED TOGETHER!


You should always use an appropriate water conditioner in your coir peat while soaking before mixing it into the sand.

You can read more about mixing substrate here, as well as the benefits of setting up the correct substrate.


----- You can read more about substrate here ----->


2 x Deep Pools

This one always gets the new owners. Hermit Crabs NEED deep water! They must be able to fully submerge their shell to fill it up with water. They will hold water inside the back of their shell. This helps their soft abdomen to stay moist and helps them to get through moulting.


You can use literally ANYTHING for your pools. As long as it is sturdy and leak proof. Tupperware containers, glass fish tanks, acrylic containers etc.

Yes, it is true that land hermit crabs can drown, but if you provide a safe way in and out of your pools, they will not drown. Some owners have pools as big as 10-20L and have had no issues with their hermit crabs drowning as they ensure they have a sturdy ladder in and out. Items you can use include rocks, plants, fish egg crate, gutter guard, ramps, wood etc.


----- You can read more about pools here

----->


High Quality Marine Salt

Hermit Crabs need marine salt in their salt pool to mimic the natural ocean. Salt pools provide the correct salinity for their shell water, as well as providing vital vitamins and minerals that they need. Marine salt is the only salt that they need. Avoid aquarium salt, sea salt, salt flakes, pet store crab salts, Himalayan salt, table salt, cooking salt, Celtic salt etc. These products are not safe and do not mimic the natural salinity of the ocean.


Water Conditioner

There are certain chemicals and heavy metals in tap water that are toxic to hermit crabs, therefore we must remove those before the water is considered safe. These include Ammonia, Chlorine, Chloramine, Nitrites, and Nitrates.

There is really only one brand that we recommend across the board because it removes EVERYTHING in just 1 drop per litre. Seachem Prime Water Conditioner. This is readily available online and in most pet stores/aquariums. Both pools should be treated with Prime.


Bottled water is not always safe either, this is often treated with Chlorine to make it safe to drink and should still be treated.


Thermometer/Hygrometer

It is vitally important to have a digital thermometer/hygrometer gauge in your tank to monitor the temperature and humidity levels. This is best placed in the middle of the tank, around 2-3cm above the substrate. This will give the most accurate reading. There are many different devices to meet all budgets. Cheaper digital readers as well as pricier Bluetooth readers that connect to your phone and monitor when you are not around.


Temperature

In captivity, our Australian hermit crabs thrive with temperatures between 27-32.c degrees. Anything below 26.c and they will start to feel cold and can be forced into an unnatural hibernation which could kill them.

Anything above 32.c degrees for too long and they will start to show signs of overheating. With the correct heat source, temperatures are easy to keep within the right parameters. You will also notice your crabs will become more active during the day if you keep your temperatures in the correct limits.


Humidity

Humidity is vitally important for your crab to survive. Land Hermit Crabs do not breathe fresh air like people do, they absorb oxygen through humidity, through their modified gills. This is how they breathe. Australian hermit crabs need humidity levels between 70-85% at all times. If this drops below 70%, they can and will struggle to breathe. Do not stress if it goes above 85%, this only causes more moisture in the tank and excess condensation. It will level out over time as the new tank settles.


----- You can read more about humidity here ----->


Heat Sources

This depends on where you live in Australia, but most places still require some form of heat source. We only recommend heat mats or heat cords. Never heat lamps, heat bulbs, heat rocks etc. These are not efficient in heating the tank and can cause substrate to dry out and burn crabs.

Heat sources should be placed on the outside of the tank, above the substrate line. Do not place your heat source under the tank, this will dry out the substrate and can burn moulting crabs. You only want to heat the air in the tank, not the sand.


----- You can read more about tank heat here ----->


Shells

We recommend providing at least 6 spare shells per crab so that they have an assortment to choose from. Choose shells that are suitable for their current size, and shells slightly larger for them to grow into.

Avoid painted shells, these are toxic and if the paint chips off and is consumed this can make your crab very sick. All natural shells are safe and preferred by hermit crabs.


Shell preferences -

  • Babylonia Shells

  • Land Snail Shells

  • Pila Ampullacia Shells

  • Turbo Shells

  • Natica Shells

  • Whale Eye Shells


----- You can read more about shells here

----->

Shell Guide -

Measuring Shells -


High Quality Food Mixes

Providing a high quality and balanced diet is essential to keeping healthy hermit crabs. You need to fill all of their dietary needs such as protein, calcium, beta-carotenes, fibre, carbohydrates, healthy fats, anthocyanins, tannins, aquatic plant matter. Easier said than done. While you can feed fresh foods, it can be hard to cover ALL of those dietary needs in one meal. This is why it is recommended to use high quality premixes from a reputable hermit crab food seller online or on Etsy, they ensure that their mixes cover all basis and contain safe and healthy ingredients. Store foods DO NOT cover their entire dietary needs and lack in certain important nutrients. Lacking in certain nutrients can cause your crab to become sick, lethargic, stressed and even go as far as attacking and consuming their tank mates to gain those extra nutrients.


Enrichment

Also known as the lifestyle of your crabby. Giving them safe and dark places to

hide like caves, and fun activities to do such as a wheel, hammocks, swings, greenery, bridges etc. Will give them something to do during their time on the surface and can keep them entertained for hours. This also gives them a more natural lifestyle and makes them feel more comfortable, safe and secure inside their tank.


Light Source

Adding a light source to the top outside of the tank will mimic their natural day/night cycle. 12 hours of day and 12 hours of night. Simple LED aquarium lights are perfect for this. Being nocturnal, you may notice them more active at nighttime.


----- You can read more about tank setup here ----->

Tank Setup Guide -


Water Conditioner & Marine Salt -


Moulting

Hermit Crabs need to moult (shed their exoskelton) in order to grow. This is an extremely delicate process and can be a matter of life or death for your crab.

This process should ALWAYS take place underneath the sand, away from direct light and other crabs. This is why it is so important to provide deep substrate at the correct ratio and sand castle consistency. Crabs will create a moult cave deep within the sand and will spend weeks to months in there shedding. During this time they won't move much and will rely on their moult sacs to survive. A moult sac is a small grey bubble on the left side of the crab, filled with foods and water to get them through the long time underground.

If a crab is disturbed during this process by another crab or humans, it can result in death. Once a crab sheds their exoskeleton, they will be extremely soft and pale. They will then consume their old exoskeleton which is filled with calcium and their new exoskeleton will begin to harden. Once complete, they will make their way to the surface to join the rest of the colony.


----- You can read more about moulting here -----> https://www.happyhermie.com.au/post/hermit-crab-moulting-what-to-know


Diet

A Hermit Crabs diet is absolutely crucial to raising healthy hermies. It may come as a surprise that hermit crabs are Omnivores. They eat plant matter, fruits, vegetables, and meat! Hermit Crabs need atleast 50% protein in their diet everyday.

They should also have plenty of calcium, beta-carotenes, carbohydrates, fibre, omega-3 fats, anthocyanins, aquatic plant matter, tannins and supplements in their diet. This is very important to ensure your crabs maintain a healthy lifestyle.


You can ensure that their diet is balanced by offering them high quality premade mixes from Australian sellers, and offering fresh foods on the side.


The below ingredients cover each nutritional aspect.


Protein

Meat, Seafood, Nuts, Chickpeas, Oats, Spirulina, Lentils, Quinoa, Eggs, Insects, Beans, Seaweed.


Beta-Carotenes

Fruits, Vegetables, Seeds, Nuts, Hemp, Egg Yolk, Flowers, Leaf Litters, Berries.


Calcium

Cuttlefish Bone, Star Fish, Sea Urchins, Sea Biscuits, Shells, Insects, Egg Shell, Coral, Broccoli, Spinach, Sesame Seeds, Sardines, Kale, Nuts, Seeds, Molasses, Shrimp.


Carbohydrates

Sweet Potato, Grains, Quinoa, Pumpkin, Oats, Lentils, Brown Rice, Buckwheat, Pasta, Banana.


Fibre

Chia Seeds, Oats, Almonds, Barley, Popcorn, Physillium Husk, Flaxseed, Millet, Wheatbran, Chickpeas, Grains, Barley.


Omega-3 Fats

Avocado, Oily Fish, Egg Yolk, Coconut, Insects, Hemp, Flaxseed, Oysters, Sunflower Seeds, Nuts, Oils.


Anthocyanins

Strawberries, Raspberries, Blackberries, Raisins, Beetroot, Cherry, Blueberries, Mulberries, Prunes.


Aquatic Plant Matter

Seaweed - Nori, Sea Lettuce, Dulse, Bladderwrack, Kelp, Irish Moss, Wakame.


Tannins

Leaf Litters


Supplements

Greensand, Worm Castings, Insect Frass


Foods they DONT enjoy (they are toxic)

Garlic, onion, chocolate, candy, additives, preservatives, chemicals, added sugars, added flavours, cinnamon, eucalyptus, pesticides, table and cooking salts, rosemary, dill, aniseed, vanilla, thyme, peppermint, bay Leaves, citrus leaves and wood, ginger.


----- You can read more about safe and unsafe foods and nutrition here ----->

Safe and Unsafe Foods -


Hermit Crab Nutrition -


Behaviour

Hermit Crabs display many different behaviours, some normal and some not so normal.


Normal Behaviour -

• Digging

• Climbing

• Bathing/Swimming

• Excessive Eating

• Sleeping

• Changing Shells

• Hiding and Shyness

• Flicking/Pushing Eachother

• Antennae Fights

• Shell Alterations

• Excessive Excercise


Not Normal Behaviour -

• Going Naked (without a shell)

• Aggression

• Lethargy

• Shell Jacking (stealing other hermit crabs shell)

• Surface Moulting

• Dropping Limbs

• Killing Eachother


----- You can read more about behaviour here -----> https://www.happyhermie.com.au/post/hermit-crab-behavior-s


Emergencies

Emergencies can and do occur inside your Hermit Crabs tank. This is why it is important to monitor your crabs every day.


Emergencies include -

• Naked Hermit Crab

This is when a Hermit Crab drops their shell and wanders around the tank naked. If they do not take a shell, they will die.

• Surface Moulting

This is when a Hermit Crab attempts their moult on top of the substrate (surface) this is incredibly dangerous and makes them an easy target to be attacked by other crabs and killed.

• Substrate Flood

When a pool of water builds on the bottom of the tank (under the substrate) this can cause moulting crabs to drown.

• Ant Infestation

When ants find their way inside the tank and start multiplying. They can attack and consume moulting crabs.


These are all situations where you will need to intervene immediately.


----- You can read more about emergencies here ----->


Naked Hermit Crab -


Surface Moulting -


Hands Off Pet

As much as we would all love to hold, play and snuggle with our crabbies. It's just not ideal. Handling your hermit crabs continually causes them an incredible amount of stress.

Letting them run around on the floor, couch, bed, table etc is also not safe.

They can come into contact with house chemicals which can transfer toxins to the crab and back into the tank.

They are also not shy in giving you a good pinch to tell you to back off, this not only hurts, but can draw blood.


They will also struggle to breathe when removed from their high humidity tank.


----- You can read more about handling here -----> https://www.happyhermie.com.au/post/hermit-crabs-the-hands-off-pet


Other Helpful Blogs

Hermit Crab Myths


FAQ'S


Bringing Home A New Hermit Crab


Australian Hermit Crabs (Coenobita Variabilis)


Checking The Gender Of Your Crab


Why We Dont Dig Up Hermit Crabs


What To Avoid When Buying Hermit Crab Supplies


Final Note

We know that the information you have read is going to be super overwhelming, especially if you have already been given so much incorrect advice from the pet store or Google. Perhaps you already have a tank setup and have now realised how inappropriate it is and you are beginning to stress about what to do now.


Stop, CHILL! We have ALL been there! Including yours truly. I started with a tiny 20L tank and 3 hermit crabs living on tanbark too. We have all been misled when we started this journey. The most important thing now is that you know, and you can now start to make changes to set your crabitat up the right way. You don't need to rush out and buy everything in one go. Small changes are perfectly fine. Start with the most crucial ones. Substrate, Pools, Diet, Heat, Humidity. Then you can work on upgrading to a larger tank for the space that they need, and then comes the really fun part. Enrichment!! Once you have your basics done, then you can go crazy with the decorating and tank enrichment.


Remember not to beat yourself up, if you are here, reading this blog, it shows you care enough to make the changes and make a difference between life and death in your Hermit Crabs lives. And that is awesome!!

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