A Complete Beginners Guide To Owning Australian Hermit Crabs
- thehappyhermie
- Jan 21, 2024
- 11 min read
Updated: Jul 14
Welcome to what I refer to as the "Crab Cult." Why this name? Because you will soon become captivated! Over the past 20 years, hermit crab ownership has evolved significantly, and we have gained extensive knowledge about the proper care of these creatures. Unfortunately, the hermit crab industry has not made similar strides in educating about proper husbandry. However, rest assured, our community has made significant progress in this area!
In the following guide, we provide a comprehensive introduction to owning hermit crabs. Soon, you will become a confident owner, ensuring your group of crabs enjoys the best possible life in captivity.
The Australian Land Hermit Crab (Coenobita Variabilis)
In Australia, there is one species of land hermit crab available in captivity: the Coenobita variabilis. A few years ago, it was possible to purchase Strawberry hermit crabs (Coenobita perlatus); however, they are no longer available for purchase in the country. Consequently, most hermit crab owners now have the Coenobita variabilis species in their tanks.
Our species require distinct care compared to their overseas counterparts, which often leads to confusion among new owners. Frequently, individuals rely on advice from Google, US-based hermit crab Facebook groups, or YouTube. It is crucial to ensure that the guidance you follow pertains specifically to our Australian species. All information provided in our blogs is tailored to Australian hermit crabs.
Quick Facts
Hermit crabs can live up to 15 years in captivity with proper care, and sometimes even longer.
Australian land hermit crabs (Variabillis) exhibit a color range from light beige and grey to dark browns and reds.
To grow, hermit crabs must shed their outer exoskeleton through a process known as moulting.
As omnivores, hermit crabs consume both plant matter and animal proteins. Their diet includes fruits, vegetables, plant matter, grains, meats, and seafood.
Despite their name, hermit crabs are highly social creatures and should be housed with other hermit crabs to prevent loneliness.
Basic Care Requirements
Outlined below are the fundamental requirements necessary to ensure the survival and well-being of your hermit crabs.
Glass tank with a glass lid, providing a minimum of 38L of space PER crab
Deep substrate with a minimum depth of 6" (15cm)
Two deep pools with entry and exit access, containing both marine saltwater and freshwater
High-quality Marine Salt
Seachem Prime Water Conditioner
Thermometer/Hygrometer for monitoring temperature and humidity levels
Heat source, limited to heat mats or heat cords
Insulation mat, placed over the top of your heat source
Six spare natural shells per crab; avoid painted shells
Food Bowl
High-quality handmade food mixes from an Australian supplier
Hides providing a safe and dark place for crabs to retreat
Enrichment items such as activities, climbing structures, wheels, hammocks, and nets
Light source set to 12 hours on and 12 hours off, using an aquarium light
Tank
Glass aquariums with lids are ideal, and secondhand tanks are highly recommended. They are cost-effective and efficient. It is essential to provide at least 38L of space per crab to prevent overcrowding, which can result in aggression and mortality.
Unsure how to calculate the volume of your tank in liters? Visit the website below, where you can input your tank's length, width, and height to determine its capacity in liters.
Substrate
Properly setting up your substrate from the outset will not only save you significant time and physical discomfort but also reduce costs. The substrate should consist of simple play sand and coir peat, both of which are available at Bunnings and most hardware or gardening stores. Our Australian crabs prefer a ratio of 8:1, meaning 8 parts of play sand to 1 part of damp coir peat. This composition ensures the substrate has the ideal sandcastle consistency and aids in maintaining humidity and adequate moisture for successful moulting. Do not confuse this with the 5:1 ratio used by our US counterparts; we require an 8:1 ratio. Additionally, your substrate should be at least 6 inches (15cm) deep to provide sufficient space for safe moulting.
Ensure that play sand and damp coir peat are thoroughly mixed until no large chunks of coir peat remain. There SHOULD NOT be separate areas for sand and coir peat; they must be fully integrated into a single sand/coir peat mixture.
It is essential to utilize a suitable water conditioner when soaking coir peat prior to integrating it with sand.
For further information on substrate mixing and the advantages of establishing the correct substrate, please refer to this resource.
----- You can read more about substrate here ----->
2 x Deep Pools
This aspect often surprises new owners: Hermit crabs require deep water. They must be able to fully submerge their shells to fill them with water. This allows them to retain water inside the back of their shells, which helps keep their soft abdomens and gills moist and aids them during moulting.
For your pools, you may utilize virtually any container, provided it is sturdy and leak-proof. Options include Tupperware containers, glass fish tanks, and acrylic containers.
While it is true that land hermit crabs are at risk of drowning, ensuring a safe entry and exit from the pools can prevent this. Some owners maintain pools as large as 10-20 liters without issues, by providing a robust ladder for the crabs. Suitable materials for this purpose include rocks, plants, fish egg crates, gutter guards, ramps, and wood.
----- You can read more about pools here
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High Quality Marine Salt
Hermit crabs require marine salt in their salt pool to replicate the natural ocean environment.
Salt pools ensure the appropriate salinity for their shell water and supply essential vitamins and minerals. Only marine salt should be used, as it is the sole type necessary. Avoid using aquarium salt, sea salt, salt flakes, pet store crab salts, Himalayan salt, table salt, cooking salt, Celtic salt, and similar products. These alternatives are unsafe and do not accurately replicate the ocean's natural salinity.
Recommended Brands:
Red Sea Salt
Aquaforest Sea Salt
Aqua One Synthetic Reef Salt
Continuum Reef Crystals,
Aquasonic Premium Sea Salt.
Instant Ocean
Water Conditioner
Tap water contains certain chemicals and heavy metals that are harmful to hermit crabs, necessitating their removal before the water can be deemed safe. These substances include ammonia, chlorine, chloramine, nitrites, and nitrates.
We recommend one brand universally, as it effectively eliminates all contaminants with just one drop per liter: Seachem Prime Water Conditioner. This product is widely available online and in most pet stores or aquariums. Both pools should be treated with Prime.
Bottled water may not always be safe, as it is often treated with chlorine to ensure its safety for consumption and may still require further treatment.
Thermometer/Hygrometer
It is essential to have a digital thermometer/hygrometer gauge in your tank to accurately monitor temperature and humidity levels. The optimal placement for this device is in the center of the tank, approximately 2-3 cm above the substrate, to ensure precise readings. A variety of devices are available to suit all budgets, ranging from affordable digital readers to more expensive Bluetooth-enabled models that connect to your phone for remote monitoring.
Temperature
In captivity, Australian hermit crabs thrive at temperatures ranging from 27-32°C. Temperatures below 26°C may cause them to feel cold, potentially leading to an unnatural hibernation that could be fatal.
Prolonged exposure to temperatures above 32°C can result in signs of overheating. With an appropriate heat source, maintaining temperatures within the optimal range is straightforward. Additionally, your crabs are likely to be more active during the day if the temperature is kept within the correct limits.
Humidity
Humidity is crucial for the survival of your crab. Land Hermit Crabs do not breathe fresh air as humans do; instead, they absorb oxygen through humidity via their modified gills. This is their method of respiration. Australian hermit crabs require humidity levels to be consistently maintained between 70-85%. If the humidity falls below 70%, they may experience difficulty in breathing. However, if it exceeds 85%, there is no need for concern as it merely results in increased moisture and condensation in the tank, which will stabilize over time as the new tank acclimates.
----- You can read more about humidity here ----->
Heat Sources
The need for a heat source in Australia varies by location, but most areas still require one. We recommend using heat mats or heat cords exclusively. Avoid using heat lamps, heat bulbs, or heat rocks, as they are inefficient for tank heating and can lead to substrate drying and potential harm to crabs.
Heat sources should be positioned outside the tank, above the substrate line. Do not place the heat source beneath the tank, as this can dry out the substrate and pose a risk to moulting crabs. The goal is to heat the air within the tank, not the sand.
To ensure effective insulation and retain heat within the tank, it is crucial to place an insulation mat over the heat source.
----- You can read more about tank heat here ----->
Shells
We advise supplying a minimum of six spare shells per crab, ensuring a variety for selection. Select shells appropriate for their current size, as well as slightly larger ones to accommodate growth.
Avoid using painted shells, as they are toxic. If the paint chips and is ingested, it can cause severe illness in your crab. Natural shells are safe and are 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
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Shell Guide -
Measuring Shells -
High Quality Food Mixes
Providing a high-quality and balanced diet is crucial for maintaining the health of hermit crabs. It is important to meet all their dietary requirements, including protein, calcium, beta-carotenes, fiber, carbohydrates, healthy fats, anthocyanins, tannins, and aquatic plant matter. Achieving this balance can be challenging. While fresh foods can be offered, it is difficult to satisfy all their nutritional needs in a single meal. Therefore, it is advisable to use high-quality premixes from reputable hermit crab food suppliers online or on platforms like Etsy. These suppliers ensure their mixes are comprehensive and contain safe, nutritious ingredients. Store-bought foods often do not meet the full range of dietary requirements and may lack essential nutrients. A deficiency in certain nutrients can lead to illness, lethargy, stress, and even aggressive behavior, such as attacking and consuming tank mates, as hermit crabs seek additional nutrients.
Enrichment
Enhancing the habitat of your crabs involves providing safe, dark hiding spots such as caves, along with engaging activities like wheels, hammocks, swings, greenery, and bridges. These additions offer stimulation during their time on the surface, keeping them entertained for extended periods. Moreover, this approach fosters a more natural lifestyle, ensuring they feel comfortable, safe, and secure within their tank.
Light Source
Installing a light source on the top exterior of the tank will replicate their natural day/night cycle, with 12 hours of daylight and 12 hours of darkness. Simple LED aquarium lights are ideal for this purpose. As they are nocturnal, you may observe increased activity during nighttime.
----- You can read more about tank setup here ----->
Tank Setup Guide -
Water Conditioner & Marine Salt -
Moulting
Hermit crabs must undergo moulting, the shedding of their exoskeleton, to facilitate growth. This process is highly sensitive and can be crucial for the survival of the crab.
Moulting should always occur beneath the sand, away from direct light and other crabs. Therefore, it is essential to provide a substrate of adequate depth, with the correct ratio and consistency akin to sandcastle sand. Crabs will construct a moulting cave deep within the sand, where they will remain for weeks or even months. During this period, they will be mostly inactive, relying on their moult sacs for sustenance. A moult sac is a small grey bubble located on the left side of the crab, containing food and water to sustain them during their extended time underground.
Disturbance by other crabs or humans during this process can be fatal. After shedding their exoskeleton, crabs are extremely soft and pale. They will consume their old exoskeleton, which is rich in calcium, to aid in the hardening of their new exoskeleton. Once this process is complete, they will return to the surface to rejoin the colony.
----- You can read more about moulting here -----> https://www.happyhermie.com.au/post/hermit-crab-moulting-what-to-know
Diet
The diet of hermit crabs is essential for maintaining their health. Interestingly, hermit crabs are omnivores, consuming plant matter, fruits, vegetables, and meat. It is important that hermit crabs receive at least 50% protein in their daily diet.
Additionally, their diet should be rich in calcium, beta-carotenes, carbohydrates, fiber, omega-3 fats, anthocyanins, aquatic plant matter, tannins, and supplements. These components are crucial for ensuring that your crabs lead a healthy lifestyle.
To ensure a balanced diet, provide high-quality premade mixes from reputable Australian sellers, complemented by fresh foods.
The following ingredients address each nutritional requirement.
Protein
Animal Meat, Seafood, Nuts, Chickpeas, Oats, Spirulina, Legumes, 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, Legumes, Brown Rice, Buckwheat, Pasta, Banana.
Fibre
Chia Seeds, Oats, Almonds, Barley, Popcorn, Psyllium Husk, Flaxseed, Millet, Wheat bran, Chickpeas, Grains, Barley.
Omega-3 Fats
Avocado, Oily Fish, Egg Yolk, Coconut, Insects, Hemp, Flaxseed, Oysters, Seeds, Nuts, Oils, Mussels.
Anthocyanins
Strawberries, Raspberries, Blackberries, Raisins, Beetroot, Cherry, Blueberries, Mulberries, Prunes, Carrot.
Aquatic Plant Matter
Nori, Sea Lettuce, Dulse, Bladderwrack, Kelp, Irish Moss, Wakame, Green Laver, Spirulina, Chlorella.
Tannins
Leaf Litters
Supplements
Greensand, Worm Castings, Insect Frass, Azomite, Bee Pollen.
Foods to Avoid Due to Toxicity
Garlic, onion, chocolate, candy, additives, preservatives, chemicals, added sugars, added flavors, cinnamon, eucalyptus, pesticides, table and cooking salts, rosemary, dill, aniseed, vanilla, thyme, peppermint, bay leaves, citrus leaves and wood, ginger and plenty more.
----- You can read more about safe and unsafe foods and nutrition here ----->
Safe and Unsafe Foods -
Hermit Crab Nutrition -
Behaviour
Hermit crabs exhibit a variety of behaviours, some of which are typical, while others are atypical.
Typical Behaviors:
• Digging
• Climbing
• Bathing/Swimming
• Overeating
• Sleeping
• Changing Shells
• Hiding and Shyness
• Interacting by Flicking/Pushing Each Other
• Engaging in Antennae Fights
• Modifying Shells
• Engaging in Excessive Exercise
Abnormal Behavior:
• Being without a shell
• Displaying aggression
• Exhibiting lethargy
• Engaging in shell theft (taking another hermit crab's shell)
• Moulting on the surface
• Losing limbs
• Engaging in lethal interactions
----- You can read more about behaviour here -----> https://www.happyhermie.com.au/post/hermit-crab-behavior-s
Emergencies
Emergencies can arise within your hermit crab tank, making it essential to monitor your crabs daily.
Emergency Situations Include:
• Naked Hermit Crab
This occurs when a hermit crab abandons its shell and roams the tank without protection. Without a shell, the crab is at risk of death.
• Surface Moulting
This situation arises when a hermit crab moults on the surface of the substrate. This is extremely dangerous as it exposes the crab to potential attacks from other crabs, which can be fatal.
• Substrate Flooding
This happens when water accumulates at the bottom of the tank, beneath the substrate, posing a drowning risk to moulting crabs.
• Ant Infestation
This occurs when ants invade the tank and begin to proliferate, threatening moulting crabs by attacking and consuming them.
Immediate intervention is required in all these situations.
----- You can read more about emergencies here ----->
Flood & Ant Infestation - https://www.happyhermie.com.au/post/hermit-crab-emergencies-flooding-bug-infestation
Naked Hermit Crab -
Surface Moulting -
Hands Off Pet
While the desire to hold, play with, and cuddle our hermit crabs is understandable, it is not advisable. Frequent handling of hermit crabs subjects them to significant stress.
Allowing them to roam on surfaces such as the floor, couch, bed, or table is also unsafe.
There is a risk of exposure to household chemicals, which can transfer toxins to the crab and subsequently back into their habitat.
Additionally, hermit crabs are known to pinch if they feel threatened, which can be painful and may even draw blood.
They will also experience difficulty breathing when taken out of their high-humidity environment.
----- 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 Don't Dig Up Hermit Crabs
What To Avoid When Buying Hermit Crab Supplies
Final Note
We understand that the information you have encountered can be quite overwhelming, particularly if you have previously received incorrect advice from the pet store or online sources. If you already have a tank setup and have now realized it may not be suitable, you might be concerned about the next steps to take.
Please remain calm. We've all experienced this situation, myself included. I began with a small 20L tank and three hermit crabs living on tanbark. Many of us were initially misinformed when we embarked on this journey. The key thing now is that you are aware and can begin making adjustments to properly set up your crab habitat. There's no need to purchase everything at once. Incremental changes are perfectly acceptable. Start with the most essential elements: substrate, pools, diet, heat, and humidity. Once these are addressed, you can consider upgrading to a larger tank to provide the necessary space. Then comes the enjoyable aspect: enrichment! After establishing the basics, you can focus on decorating and enhancing the tank.
Remember not to be too hard on yourself. If you are here, reading this blog, it demonstrates your commitment to making changes that can significantly impact the well-being of your hermit crabs. That is truly commendable.
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