General Hermit Crab Care Information and Tips

 There are thousands of species of hermit crabs, however, land hermit crabs are generally of the Coenobita species.  The most common species found as pets is  the Coenobita Clypeatus or "Purple-Pincher" named for the often purple colored large claw. However purple-pinchers can have varying colors. These crabs can be distinguished among their species by several characteristics which include color, size, markings and shapes and sizes on the claw. They may have differing behavioral tendencies and climate preferences by species. For example, Coenobita Compressus or "Ecuadorian" crabs tend to be smaller, gray color, very lively and active and Coenobita Perlatus or "Strawberry Crab" tend to be more delicate and prefer warmer climate and saltwater submersion. Check out our Cute Hermies board on Pinterest  for beautiful photos of the different species from various sources, and for pinned articles from various sources in the Hermit Crab Tips and Care board which help you to determine which species you have.

Land and aquatic hermit crabs may be kept as pets, either in an aquarium or a terrarium environment, depending on their species.  Although hermit crabs are a crustacean and have been on earth in the same form for millions of years, they have only more recently became kept in homes as pets. We are still discovering the best ways to maintain these animals, they are always wild captured, and they do not generally breed in captivity. However, some skilled crab keepers have accomplished successful breeding. Land hermit crabs must live in the ocean for their early development and begin their land phase as adult hermit crabs. Knowledge of the conditions which these special creatures thrive in is crucial for keeping them alive and healthy.  Under ideal conditions, they have a long lifespan (30 - 40 years) so they can easily be your companion longer than a dog or a cat. Ongoing research and personal experience by longtime crab keepers have revealed important information that we can use to keep our crustacean pets healthy. Since these animals survive by living in and changing shells (created by snails) and grow by molting and shedding their exoskeleton, proper care means ensuring that their environment reflects this continual need throughout their lives.








- A species companion - at least one or two additional hermit crabs of the same species to keep each other company. Normally they survive in colonies in the wild and count on each other for food, resources, shells, etc.  A single hermit crab does not usually survive well kept alone in captivity, even if all other requirements are met.

-An adequate sized tank - Approximately three to five gallons per crab for small to medium sized crabs.  Some species ("Ecuadorian") and jumbo crabs have larger tank requirements given their activity and molting requirements. A ten gallon tank is usually sufficient for two crabs but a 20 gallon is better. More space will reduce other issues that may arise when keeping crabs.

-A humid environment -  These animals must have humidity above 70% at all times because they breathe through modified gills and can not breathe dry air. They can suffocate if left out of a humid environment. This is so important that a hygrometer to measure humidity should be present in the tank at all times. Using a glass or plexi-glass tank with a mesh lid covered with plastic wrap or a full tank lid is recommended.  Also keeping the sand moist, adding coco-fiber or moss will help trap the moisture inside. To prevent mold, ensure some air circulation into the tank and keep the moisture below 80%  

-A warm environment - As cold-blooded animals they must maintain their temperature by the environment. The tank should be warm and a thermometer should be present at all times, usually the home environment is cooler than what the crabs normally live in. They can hibernate and eventually die if they become too cold. Generally above 75 degrees Fahrenheit  is safe, although it should be kept warmer for various species. A tank heater or incandescent bulb will help with this. However, be sure to guard against overheating as well (greenhouse effect).

-Regular Lighting - Although they are usually nocturnal, having a normal cycle of day and night is helpful so natural lighting or artificial lighting will help them adjust to their new environment if it alternates between day and night. 

-Clean Fresh Water and Ocean Water Pools -  This water for drinking and bathing cannot contain heavy metals or fluoride which the hermit crabs cannot tolerate-  it will cause their premature death. Use dechlorinator and/ or boiling water to remove amines, however this does not remove fluoride.  In locales where the water source is fluoridated, (i.e. New York City), tap water should not be used. Poland Spring or other  bottled water should be used instead. Instant Ocean and or other brands of aquarium saltwater pre-mixed (or you can mix it yourself using bottled water to the correct specific gravity) should be used for the saltwater pond. Do not use table salt which is harmful to the crabs.



-Deep Substrate -  This substrate should be playsand or eco-earth or coconut fiber/earth or a mixture of sand and earth- mixed with dechlorinated water consistent with their natural habitat. Avoid gravel, calci-sand, hermit crab sand, walnut shells, or reptile sand as sold in pet stores. These other substrates will harm the crab with the texture and prevent successful burrowing and molting .  The sand/earth should be sandcastle consistency not dry or muddy and it should be six inches or two to three times as deep as the largest crab.  This is so they can dig caves and tunnels to burrow and molt undisturbed.

***Hiding and Climbing Toys - They are shy animals (generally) and will need regular places within the tank to hide and sleep under. However, many also love to climb and would do so often when given the chance. Having these elements in their tank will help them adjust and thrive. Cholla wood, branches, vines, nets, coconut huts serve this purpose - and make designing a crabitat fun! Natural elements instead of painted ones are safer for the crabs.  

-Shells! - Hermit crabs must have regular access to appropriate sized shells slightly larger and smaller than their own so they may change into them as they need to. One clue they may need a larger shell is when they cannot fully retract their entire body into and block the entrance with their large claw.  Or their shell may be too large and they will rest deep in the shell and have a difficult time maneuvering.  The shells should not be painted as any paint will chip and they will eat it and it will poison them. If they are in a painted shell, offer them new natural unpainted shells and once they switch into the better shell, remove the painted shell from their access. Also understand that they they may fight each other aggressively over shells because it is a matter of survival for them; so be sure to keep the supply adequate and separate them into different tanks if necessary.













- Each hermit crab ("hermie") has it's own unique personality - the location where it likes to hang out in the tank, the foods it prefers, and how it generally behaves. Don't force or expect a certain behavior from your hermit crabs, just observe them to see how they relate to you and their fellow crab tank mates in order to be sure their needs are met.  Be patient and be attentive. This will be the best way for you to determine if anything is needed, i.e. new shells, more space, more food variety, a new hiding space, etc.

- Have another small tank ready to use  set-up with the proper conditions - for use as isolation for molting crabs if necessary,  for separating quarreling crabs, for when deep cleaning the main tank,  for transporting the crabs, or just giving them a change of scenery.

-Regularly take notice of the way the the normal crabitat smells - this can provide more information for better care. Generally the tank should not have much of an odor at all (except the odor of whatever food for the day).  If the tank has an unpleasant odor it could signify rotten food hidden somewhere, too much humidity with mold or bacteria growth, a chemically treated product which is releasing fumes, or in the worst case scenario a dead crab. 

***Take your hermit crabs out of the cage to explore and become used to being around humans, however don't overstress them. Allow them exercise and a change of environment to allow stimulation and prevent boredom.  They are naturally climbers and explorers and may travel great distances. If it is warm and safe take them outside in a natural environment or garden - as long as no chemicals are used to maintain it - ensure they are visualized at all times; consider making a "leash" for them. Guard them around family pets (cats and dogs) and other predators which may treat them as prey. Keep an eye on the time they are out of their warm, humid safe environment. Watch them carefully so they don't get lost. Keep them away from any chemicals, especially pesticides and insecticides as they are very sensitive to and can be harmed or killed by these; even the fumes of cleaning products may be detrimental. Some crab owners don't endorse handling or removing them from the tank, and will instead provide stimulation and exercise opportunities for their crabs within the crabitat.

*** Handle the crabs gently, and speak to them gently to encourage them to trust. When they feel comfortable, they will crawl onto your open palm and may even eat food that you offer them on a spoon (don't use your fingers as they pinch with their claws to eat). Be careful not to drop them or make them feel unsteady or they may pinch you to hold on.

***Feed them a healthy diet of a diverse variety of food items -  raw fresh fruits, vegetables and cooked meats, but also dried insects, dried shrimp, worms, flowers and leaves. They are omnivores and have varied nutritional requirements. Many processed foods (including foods sold specifically for hermit crabs) have chemicals, dyes and preservatives which can kill the crabs. Even some natural items, such as pine wood can be harmful to the crabs - so be careful which foods they are given to eat and which items are placed in the crabitat (they will nibble on or sample various items in their environment, even fake plants). Check with sources to determine which foods and items have been deemed safe. Some foods will help them display beautiful colors to their exoskeleton.

***When hermit crabs molt it is a very delicate period for them and they may not survive if not maintained correctly - in a  warm, moist, dark environment with few disturbances. Ensure the other crabs leave the molting crab in peace, hence deep substrate and a sufficient size tank are important. Isolation to another tank may be best depending on your crab care scenario, however, caution, if moved during molting, they can easily die during this period.

***Research hermit crab care from various sources to learn about the latest information regarding the best way to keep them healthy, safe and happy. As more information becomes available, some prior advice may become outdated. As such, it is important to continually remain aware of the active hermit crab care community in various media outlets and literature. Consider joining an online group, community or forum to have a trusted source of hermit crab care information and support. 

Following these guidelines will help to give your hermit crab pets the best chance at longevity and a comfortable environment, and you the opportunity to care for and enjoy these companions for many years.

***Post updated - Sep.24, 2017

Hermit Crab in crabitat touching the edge of the coco hut with his leg.

Photo Source Credit: Public domain image acquired from Pixabay.


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Brooklyn, NY, USA