Frequently Asked Questions!

My Crab's Legs are Falling Off One by One!!
Many people who bring home crabs fresh from the pet store experience this in the first month of owning them -- the crabs seem to just "fall apart" one leg at a time. Let me state for clarity, that this is not molting! What your crab is doing is responding to all the stress of being taken from his tropical home, taken to a wholesaler's and then shipped to a pet store. That is a lot of stress on any animal (even people!) and for a small animal like a hermit crab, it can have devastating consequences.

Is This Contagious?  No, it is not usually contagious, unless all the crabs came from the same place and were subjected to the same conditions. For this reason you should always select your crabs carefully, no matter where you buy them. Avoid crabs that have a musty smell (indication of overheating) and crabs that will not come out of their shells when held or misted. The ONLY exceptions to this rule are (1) if the crab has a healthy, strong pinch when you put something in his large claw, or (2) if you feel movement of the crab inside the shell as you hold him. Don't buy crabs from places where they don't have adequate food or water, or if there are flies inside the tank or on the crabs. For the safety of all your hermit crabs, newly-purchased crabs should be quarantined at least two weeks.

But What if I've had the Crabs for Longer Than a Month?  If you've had the crab for at least a month and it begins to drop legs and claws, you need to closely examine your crab-keeping practices. Refer to the basic care page to brush up on your crabbing skills. Pay particular attention to the Critical Care Tips at the bottom of the page. 

Is There Anything I can do to Help my Poor Crab?  The only thing you can do for your hermit crab is maintain an optimum environment and hope the stress wasn't lethal. I have had crabs lose a leg or part of a leg and not die. I have had crabs lose their big claws and not die, so the loss of their big claw does *not* mean the crab is "doomed." However, crabs that lose moreCrab without claws eating than one leg in a few hours are usually beyond help and you should isolate them from the others and attempt to keep them as comfortable as possible until their death. 

What Can I do to Prevent This From Happening Again?
Closely examine your crabitat. Check for the following known crab stressors: (1) low humidity; (2) tank too hot or too cold; (3) recent temperature fluctuations; (4) chlorine in the drinking water; (5) heat lamps, heat rocks or being kept in the sun too long with no place to hide; (6) chemicals in the environment, such as metal water dishes, cleaning solvents around the crabitat, (7) shell fights; (8) bathing or misting the crabs too much (more than two times a week); and (9) molting problems. You can't do much about the molting problems, but almost all the other stressors can be alleviated in some way. Please try to keep your crab's home as stress-free as possible. 

HELP! My Crab is NAKED!!
Though it's your first instinct, don't panic. Run your hands under water to remove any perfume and/or hand lotion. Try the GLASS CUP METHOD. This is something that I made up that works wonderfully.

Take the naked crab and dip him in water to wash the substrate off him. Then rinse out his old shell. Put him and his shell into a glass cup together, and put into the isolation tank and leave him alone. It keeps him from running around frantically (as naked crabbies do) and conserves his energy. Besides he is in close quarters with his shell and can't walk away from it. I've been using this method for two years now, successfully.

A second method is to calmly pick up the naked crab and dip him (and his shell of choice) into dechlorinated water and, using your finger, try to gently curl his abdomen into the shell. If he doesn't like the idea and pops out of the shell, set him down and take a good look at the shell. Put your fingertip down inside it to make sure there are no protrusions or anything which would irritate or poke his abdomen. Then, try again to place him into the shell. If you still don't have success, try a new shell the same size as his previous shell. If that doesn't work, get him into a shell that is larger. Do not under any circumstances force him into a shell that it too small or uncomfortable for him. He is already under tremendous stress, and forcing him into a shell he does not want to enter may put him into shock and eventually death. 

But WHY?  It is my experience that crabs streak (go naked) because of the following things: 

Shell Fights "Shell fights occasionally occur among wild and pet hermit crabs and can often be detected because of chirping sounds. From a position slightly above the defending crab's shell, an attacking crab seizes the defending crab with its walking legs and rapidly rotates it back and forth. While doing this, the attacker's claws are usually inside the opening of the defending crab's shell. This shaking often drives the defending crab from the shell that the attacker wants. Practically leaping out of its shell, the loser waits and enters the victor's shell. Typically, neither crab is harmed and both might get a better-fitting shell."Taken from Hermit Crabs: A Complete Pet Owner's Manual, by Sue Fox 

Environment Too Hot  I've seen crabs react to hot temperatures by having sequential shell fights down the 'intra-tank-pecking-order' until the weakest crab was left naked. This was because the crabs required a thinner shell to aide in cooling their abdomens. Keep a close watch on the temperature and make sure it does not get too hot.  In the wild, a hermit crab can go under a bush or something to cool off.  In your crabitat, they are hostage to the conditions you provide.

The Unexplained  Sometimes a crab you have had for a long time will go naked for no immediately obvious reason. In that case, you must examine your entire method of crab-keeping. The crab would not be naked if something weren't amiss. Go back and look for any possible stressors, in particular the temperature and humidity.

My Crab Tank Is Infested With Mites or Gnats! YUCK! One day you pick up your favorite crab, and as he comes out of his shell to greet you, what do you see but BUGS crawling on his back! You can't believe your eyes, blink, and look again – yep, they are still there! Your crab has mites. 

If you have a problem with small flying black insects, please scroll down to the section on gnats.

How Did I Get Mites -- The Tank is Spotless? Even the cleanest crabitats can be 'visited' by mites. They are attracted to your crab tank because it is warm and moist, and they stay there because there is food and water readily available. Once they settle in, they lay eggs and basically colonize your crabitat. There is only one way to get rid of them – tank sterilization. 

How do I Get Rid of Them? The most reliable method is to throw out all the old 'infected' substrate. While the tank is still empty, rinse it out with water. If your tank is large (20 gallons or more), you can use the 'wet paper towel' method. Moisten a paper towel with tap water. Then, pressing HARD to squish any mites, rub the towel over the entire tank. Pay special attention to the corners of the tank – which is where they hide. An alternative is to (with the tank dry or after it dries) use a vacuum cleaner hose to suck the dirt out of the corners. Allow the tank to dry thoroughly.  Mites also hate sunlight so placing an empty  crabitat out on a white blanket on a sunny day will encourage the mites to leave your crabitat

What if I Can't Afford New Substrate? If you can't afford to buy all-new substrate for your crabitat, there is another sterilization method. Preheat your oven to 300 Fahrenheit. Take the 'infected' substrate out of the tank and spread it on a cookie sheet to a depth of about inch. Bake it in the oven for hour and allow it to cool. Repeat as many times as necessary until ALL your substrate is sterile. Then clean the tank (as explained above in "How do I Get Rid of Them?"). 

But Don't the Mites 'Hide Out' in The Crabs' Toys? Absolutely. While the tank is drying, it is very important that you disinfect all the crabs' extra shells, dishes and climbing toys (like coral) by boiling them for about 5 minutes. Pieces of wood can be sterilized by putting them into either a microwave oven for about 2 minutes or a regular oven at 300 Fahrenheit. Keep a close eye on any wood you sterilize to make sure it doesn't catch on fire. It is a good idea to sterilize all crab toys in this manner before they are introduced to your crabitat to prevent the introduction of "undesirable" visitors. 

How do I Remove Mites Living on the Crabs Themselves? The best way to remove mites living on the crabs is to give each crab a full-immersion bath. Prepare them a bath in lukewarm, dechlorinated water.  Tip the crab upside down in the bathwater and get all the air bubbles out. Give them one bath, let them air dry, then give them another, etc. About two baths is usually adequate. Pour the water off the crabs, because sometimes the mites float on the surface of the bathwater, and then when you bring the crab up out of the water, the surface tension of the water allows them to hop on again. Watch the surface of the bath water for crawling things. 

What do I do With the Crabs While Their Tank is Being Sterilized? After their tank has been cleaned out, you can place a soft towel in the bottom of the tank for the crabs to hide under (they like to hide away from light also). Be sure all undertank heaters are turned OFF at this point, since there will be no substrate to insulate them from the heat source. Alternatively, you can let them roam around a room or place them in a large box or other container to get some exercise. 

How do I Prevent the Mites from Returning?  The best method of mite prevention is to eliminate anything that could possibly attract them. Mites are often attracted to the crabs' food. Dried shrimp and plankton-type crab food is strong-smelling and therefore a big mite attractant. Fresh food offerings that remain in the tank too long and have spoiled will also draw mites. During your weekly 'housekeeping,' remove all spoiled food from the tank. Be sure to check thoroughly -- the crabs like to bury morsels of food out of sight. Scoop up any crab droppings and check the water dishes also. Hermit crabs often use their drinking water to clean out their shells, so there may be feces fouling their drinking water. Replace the water and smell any sponges you use to help boost humidity. A clean sponge is not noticeably offensive, but a dirty sponge smells like something rotten. Additionally, the area in the vicinity of the crab tank should be kept clean and well-dusted to discourage mites. It is not advisable to grow live plants near a crab tank, since plants attract their own pests and it would be easy for the mites to travel from the plant to your crabitat. If you use a hinged glass lid, be sure to clean the back of the lid frequently with a damp towel to prevent dust buildup. The back half of a lid or hood can be taped to the rim of the tank to keep out any dust or unwanted intruders. Glass lids fit quite snugly into the tanks themselves – taping them down forms an excellent mite barrier. 

How do I Give My Crab Fresh Food Without Attracting Mites? It's easy. There are two methods: 1) Offer fresh food in a separate container outside of the crabitat. Many people give their crabs treats this way, especially if the treats are messy, like honey or peanut butter.  2) Offer fresh food only at night. Place the cut-up food in a food dish and lower it into the tank before you go to sleep. In the morning, remove the fresh food and any stray pieces of it the crabs have dragged away. Either of these methods are excellent for offering your crabs the fresh food they crave. 

Unfriendly Neighborhood Fungus Gnats They look like tiny black mosquitoes but don't bite, but they DO buzz around everything. They land on the crabs, the walls of the crabitat and they are good at getting away from you -- congratulations, you've got fungus gnats!

There are a lot of different species of fungus gnat. The genus is Mycetophila. Their lifestyle is similar to a butterfly's but not nearly as pretty! If you want to learn more about the particulars of fungus gnats, Google does a pretty good search if you put fungus gnat in quotes.

Here is a story that I posted on landhermitcrabs.com back in October 2003 about my fungus gnat problem and the solution I finally ended up using.

One day I noticed a lot of flying black bugs in the crabitats. A search on the Net told me that those little black buggers are called fungus gnats and they are attracted to damp, woodsy stuff (like house plant soil and forest bedding). Somebody had posted a link to place where you can buy "Fungus gnat predators." Basically, mites that eat fungus gnat eggs, larvae and adults.

I pondered this for about two weeks, then threw in the towel and ordered the fungus gnat predatory mites Hypoaspis miles. They came in and I dutifully dumped them out into both crabitats. Since the jumbo tank had more gnats, they got more mites. At first, I didn't see any mites in the stuff I shook out of the bottle, but after a while they started to crawl around. They are teeny tiny, some are the size of regular crab mites and others are a little bit larger. The bottle says it contains all stages of mites (egg, larvae, juvenile and adult) so that explains the size difference.

About two hours after introducing the mites to the tank, they had found the crabs. Spider had some mites crawling on his shell, but I am not worried, since they eat fungus gnats and not hermies. The fungus gnats in the jumbo crabitat were flying all over the place. Whether or not they were disturbed by the predators remains to be seen. I closed the lid on the jumbo crabitat to keep the gnats from flying out. Even if some gnats managed to make their way to the smaller crabitat, that one has predators in it too.

As of this morning (10/13/03), there is biological warfare going on in my crabitats! I noticed some struggling fungus gnats this morning, and some newly-hatched adult gnats that were having a hard time getting airborne. The predators are alive and well and, due to hermies' messy habits, well distributed throughout the entire tank.

I imagine in a couple weeks or so I will begin to notice more of a difference. The first reaction I saw was that a lot more of the gnats flew out of the crabitat. Perhaps they went over to the smaller crabitat but they will find no rest there! There are less gnats in the smaller crabitat already, which is great news!

Note that if you are obsessive about bugs, these mites do look a lot like crab mites and yes, they do crawl on the crabs. So I don't recommend these to people who get grossed out by insects. There are easily thousands of mites in that bottle and no way you will be able to get them out of the crabitat if you change your mind at the last minute. This is not for the squeamish!

My crab is digging. Is that because he's molting?
Not necessarily. Crabs dig for different reasons. Digging is sometimes the result of a crab seeking cooler or warmer conditions. Some crabs, like us, have different degrees of tolerance to heat and cold.  Crabs can raise or lower their temperature in three ways,

1) by digging into the substrate;
2) by 'hanging out' of their shells to ventilate the sensitive abdomen; and
3) by switching into a thicker or thinner shell.


In my experience, crabs prefer the heavier shells which are lined with mother-of-pearl. However, I had one crab in a very thin snail shell who refused to change shells. Each crab has its own opinion about the shell it chooses to live in! 

But I just brought him home from the pet store yesterday! A person I know who has had her pet land hermit crabs for about 15 years tells me that when she brings a new crab home, the crab buries itself in the substrate of the tank for about two weeks to 'acclimate.' So please do not automatically assume that when you bring a brand-new crab home and he buries himself, that he's molting! If you bring him home to an ideal environment, you may have saved his life! Like any animal who has been sick (from a dirty pet store), he will do himself may need some time underground in hermit-crab 'intensive care' to rest and recuperate in darkness and solitude. 

How do I know exactly what he's up to under there?
If your crab completely buries itself, one way to find out whether it's molting or just playing hide-and-seek is to smooth out the sand over and around the 'hidden' crab. Then if the crab 'comes up' at night for a drink or a bite to eat, you'll be able to tell what's going on. 

Should I mist the spot where he's buried, or do anything else?
The best advice for dealing with a buried crab is to leave it alone. Note the date your crab buried itself. If it has not surfaced after about four weeks, you can carefully brush back the sand on the crab and make sure it is still alive. If the crab is still alive and appears to have molted, carefully cover it back up with substrate. On the other hand, if you smell a nauseating odor of rotting fish, it means the crab has died, and you should dig up the corpse and dispose of it. To be sanitary, you may just want to scoop the dead crab up along with the sand it was buried in, and dispose of all of it at once.

I Bought A New Crab. How do I Introduce it to the Others?
There are lots of ways to introduce them to each other, but the most cautious method is this:  When you bring the new crabs home, give them a bath in Stress Coat-treated water, and be sure to clean out any gunk from their shells. I've actually had maggot eggs float out of crab shells, so keep an eyeball trained on the bath water. Pour the dirty bath water off the top of the crabs and repeat until you are sure the crabs are clean! If the shells the crabs are in are coated with slime or other funk, use damp dish towel to rub it off. Do not use any type of soap.

Put the new crabs into their own cage for a week or two, depending upon the degree of cleanliness of the tank they came from at the pet store. One day as a minimum, two weeks the max. This is the time to provide them with new shells and lots of fresh food and fresh and salt water If they came from squalid conditions, the crabs will more than likely eat and drink what appears to be a large amount. Don't worry, your crab won't explode -- in his primitive brain he doesn't realize that he will have this good food available to him every day -- so he is overeating and tanking up what he perceives to be tough times ahead, sort of like the squirrel storing up nuts for the winter. Try to leave the new crabs alone for a day or two to get used to their surroundings. Keep in mind how stressed you are after you move into a new house, and give your new crab a little rest.

Meet the Family
After being cleaned up, well fed and possibly changed into a better-fitting shell, it is now time to introduce your new crabs to the rest of your crab clan.  Place the new crab into the main crabitat and supervise reactions until most of your crabs have met the newbie. Make note of 'feeler fights' and pushing contests.  Crabs don't usually attack each other unless one smells like new molt and/or is wearing a desirable shell.

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2011 Christa Wilkin