INFO: Basic Hermit Crab Care

  • #1
Land Hermit crab basic care
First congratulations on deciding to care for land hermit crabs. They are fun little creatures and though complicated to care for, they are not difficult.
They need a few basic things to make them long lives in captivity.

Tank and Lid
First they need a decent size enclosure. A fish tank type is best but if you already have a wire enclosure you can modify it to make it to make it work. It needs to be a minimum of 10 gallon size for one crab. But hermit crabs are social so buy him a couple friends. Good news! Your 10 gallon tank can hold more than one crab. It can hold from 2 jumbo crabs which are roughly the size of a softball or 10 tiny crabs which are about the size of a nickel. But plan to upgrade because they will grow!

It is hard to start out at less than a 10 gallon tank just because of the many things they need in the tank. Keep reading and you will see why and if you find you really love the little guys I think you will find you will want to go bigger. Most of us do.

You will need a lid. You can use glass if desired but if you do you may find you will need a fan like this one. A good heavy wire screen lid that hinges in the middle is really nice. But whatever you get be sure it fits snuggly as your crabs are escape artists and they will even climb the silicone joints in an effort to explore. The larger ones can push light weight wire lids off with ease.

It is recommended to add Velcro to your lid as a safety measure. A couple pieces in the back and couple in front to lock it down will prevent escapes.

Now for setting up your Crabitat

You can choose to use all sand. Play sand is recommended. It is very inexpensive at about $5 for 50 lbs and it packs pretty well. However it is difficult to keep the moisture up and will require constant misting even when the humidity level in the enclosure is high.

Some owners have accidentally over misted and drowned buried crabs so be careful. Stay away from calcisand, even though it is sold in stores as hermit crab sand. It can get hard when it dries, like a rock, and trap your crab underground. It does not have the right consistency for tunneling as it caves in behind them when they dig. And it sticks to their bodies and shells.

Eco Earth, (coconut fiber) This can be used by itself but does not have a good consistency for tunneling as it does not pack well. It does hold moisture very well for long periods of time. I personally do not recommend using this product alone because it does not pack well and when a crab is underground molting it is very vulnerable to other crabs in this substrate. It is easily dug up and attacked.

What you are looking for in a substrate are the following things. You are aiming for sand castle consistency that the crabs can dig in. Substrate that will hold its moisture so you don’t have to mist it all the time, substrate that has beneficial bacteria so you have a natural cycle in the substrate much the same way we do in our fish tanks.

This is what I use and it seems to work best. It also is what most members of the Hermit Crab Association seem to prefer.

4 parts play sand - you can find this at any garden supply (the play sand does not need to be washed. Just be careful that it was not stored near chemicals at the store where you purchase it to avoid any cross-contamination)
6 parts Eco Earth or Forest Bedding (coconut fiber bedding) found at any Pet Supply
2 parts Organic worm castings –you can find these at any garden supply
1 part crushed deciduous leaf litter – you can find this in your back yard or park (be sure these are not conifers / pine trees as they will kill your crabs…

anything like oak or maple or any other leaves will work) I bring them in and bake them(low temp for 30 mins) and wash them in salt water and rinse in dechlorinated water and let them dry completely by putting in a warm oven on a cookie sheet. Then I crumble them up and mix in.

Your substrate needs to be twice as deep as your largest crab is tall plus 1 inch.

Two types of water
You will need both a saltwater and a freshwater bowl that is deep enough for your crab to get into and submerge himself… yes submerge himself. If you have enough room in your crabitat you can give your crab large pools to swim in. Smaller pools can be made by placing a Tupperware type container in the sand. Put one container inside a slightly larger one so that when you take the smaller out for water changes the sand does not cave in.

This will make for easier water changes. Be sure to create a ramp so your crab can get back out again.

This can be done with coconut matting for a natural look or plastic needlepoint canvas is often used for a very inexpensive way to make ramps. Some people use pieces of plastic and use silicone to glue shells and pebbles to create natural looking ramps. You may be surprised to find that your crabs will actually spend a fair amount of time underwater in your freshwater pool.

They will also visit the saltwater pool frequently to collect water to store in their shells. Make sure to treat your freshwater with a water conditioner that blocks heavy metals and removes chlorine and chloramine.

Here is a link for more info Different water conditoners and what they do | Water Supplements Make your saltwater exactly the same way you would for a saltwater tank, not a brackish tank. Don’t use table salt or salt for fresh water tanks. Use reef salt made for saltwater tanks. If you have a salt water tank you can take some from your existing tank. Here is an informative thread about mixing salt water .

It is up to you if you want to make a pool big enough to add live rock or sand and cycle it or if you just want to change it out every couple of days. Most people change it out every couple of days.

An easy way to do this and to be sure you get it right is to buy saltwater from the pet store in jugs that is already made for you. Most sell them for pennies a gallon. You can get by with a pool that is only a couple inches deep.

Hermit crabs store brackish water in their shells at all times to keep them hydrated. Each creates its own desired formula of brackish water depending on its own needs at the time, which changes over time. It does this by going back and forth between the two pools. That is why you need to provide both pools.

They will use both for drinking and hydrating and those needs can change over time. And example of that would be molting time, a crab will need a higher concentration of salt when it gets closer to molting and you will see it visit the saltwater pool more frequently as it gets closer to molting time.

Oh... and throw away those sponges that the pet store told you to put in the water dish. They don't need them to drink out of. That is an old wives tale. The sponge harbors bacteria and it often soaks up so much water that there is not enough left for them submerge to the point that they can fill their shells. If you feel you simply must have a sponge in the water dish then please clean it daily to prevent bacteria growth.

Humidity and Heat
Hermits actually breathe with modified gills and need their environment to be kept at a relatively high humidity. They will be more active if the temperature is higher as well. So a hygrometer and thermometer is a must. Recommended levels are 80% humidity and temperature 80-82 F.

You will probably need a heater and there are several kinds that you can use and you may even decide to use more than one. If you use an under the tank type heater, do not put it under the tank as it heats the sand and will practically cook the little guys as they molt. Instead put it on the back ABOVE the substrate. A good size one will raise the tank only about 5 degrees Fahrenheit so you may need an additional heat source.

Heat lamps are useful but tend to reduce the humidity in the tank. Be sure that you do not get a reptile light that says it is a spot light or basking light as these light are made to get really hot in one spot, not diffuse the heat over a large area. Even an incandescent light bulb might do the trick during the day if you don’t need to raise the heat much. Again, do not let this heat source get too close to the tank. Do not put a light directly on the lid even if it is made for it. If your lid is glass it can break from the heat, if it is metal screen your crabs will climb on it and be too close to the heat.

As for heat you want to aim for 82F during the day and no lower than 75F at night. Keep in mind that your crabs need a light cycle to be healthy and to molt. So turn the lights off at night. You can use a Red or Blue reptile light at night as these don't seem to bother the crabs even though they can see this spectrum. And never let the temp get below 70F.

If you have a wire cage, use saran wrap or something similar to wrap the outside of the cage to keep the humidity in. Be sure to keep any heating elements far enough away to avoid a fire. If you need to raise the humidity, try putting an air stone in your pool. You may need to put one in each pool. If that does not raise the humidity enough there are foggers available in the reptile area of the pet store that will work. Just be sure to protect them well from curious crabs.

You will need lots of shells for your crabs to change into. Hermit crabs do not make their own shells. They use whatever empty shells they can find so we need to provide suitable shells for them. Rule of thumb is to provide at least one slightly larger, one slightly smaller and one about the same size for your crab to change into.

That being said, I would like to address the fact that most crabs come home from Pet stores in shells that are grossly inappropriate in size and shape. Some have been forcibly removed from a shell that they had chosen in the wild and forced into a painted shell that does not fit properly. I have seen some tiny crabs in shells so large that I was surprised when I saw there was a crab way down inside the shell. He would change into a smaller shell given the chance. I would be surprised if he could even lift the one he was in. So choose shells with those things in mind. And the reverse it true as well, crabs in shells way too small. So give your crabs lots of choices.

If your crab does not find a shell he likes and you have taken my advice and provided him company, he may try to take a shell from a neighbor. These encounters often leave one or both of the crabs damaged. Many of my friends who have owned crabs for many years think that providing shells in a ‘shell shop’ type environment is best.

They place all shells in one place, usually in a basket or Tupperware bowl to help keep shells clean and free of sand. Most place it on a second level by securing it with command hooks and zip ties and creating a ramp of dead fall (be sure this is also from deciduous trees. Some use cholla wood for a unique look) This allows crabs to change shells without fear of attack from others while out of their shell. Choose shells wisely.

Purple Pincher Crabs (Coenobita clypeatus), the most common hermit out there will want shells with a more round 'o' opening like turbo shells... like these.

The Equadorian Hermit (Coenobita compressus) will want a shell with a more oval '0' like opening such as the sharks eye moon shells like these. Although they may consider the turbo shells as well.

The Ecuadorian or "Es" will hollow out or modify the shell as they grow and will take a long time in between shell changes. They are very fast and will choose to pick up and run, so they choose a lighter shell than the Purple Pincher "PP" who chooses a larger more fortified shell and will hunker down and wait it out when threatened. PPs will tuck back in their shells when you pick them up and close the door with their large Pincher, which is most often very Purple .

The Es have been know to jump right out of their shell and take off running naked when picked up and frightened.

Moss pit
It would be nice to provide a moss pit. Crabs love moss and this will be a popular place for your crabs to hang out. A basket or Tupperware type bowl with moss, usually sphagnum moss(not sphagnum peat moss) available at most pet stores. You can also use frog moss. This can be placed on the second level too, to help save room on the first level.

Hiding Places
Your crab will want to hide at times, both from you and from other crabs so a few little hiding places would be nice. Caves made of coconut shells upside down with a door cut in them can be found for a couple of dollars online. Reptile caves, plastic caves made for mice work well.


Your crab will eat almost anything... and I do mean anything. You will find that he loves the meaty parts of fruit such as apple, peach, pear, banana, apricot, mango and anything along those lines... He also loves cheese, yogurt, eggs including the shells which are high in calcium for him.

He will eat any of your frozen fish foods like bloodworms and brine shrimp. He loves and needs shrimp with the shell from the grocery store. He needs the exo skeleton to help make his own when he molts.

For this same reason you can feed him dead crickets or grass hoppers. He will eat flowers such as dandelion, pansy, or honeysuckle. High protein foods such as honey and crunchy peanut butter mixed together are good for him especially when he has been injured or when trying to tempt him to eat. He loves organic worm castings. Believe it or not they will eat feces of any kind and dried feces is marketed for sale for hermits... go figure! Who knew there would be a market for Moose Poop! hahaha And it is a big seller.

Things to Avoid

Any plant that is poisonous to most animals is likely poisonous to your hermit so here is that linkToxic and Non-Toxic Plants

Also when decorating your habitat avoid Conifers. They are cone-bearing seed plants with vascular tissue; all extant conifers are woody plants, the great majority being trees with just a few being shrubs. Typical examples of conifers include cedars, Douglas-firs, cypresses, firs, junipers, kauris, larches, pines, hemlocks, redwoods, spruces, and yews. If you are not sure... Google it

The skin of Avocados is toxic to hermit crabs, so is the pit

Well... in a rather large nutshell you have most of my notes on hermit crabs. I have lots more so if you have questions please ask.
  • #2
Very informative
Thanks Lorianne!
  • Thread Starter
  • #3
You are welcome! I am glad to help.
  • Thread Starter
  • #4
I was going to make a new post for Substrate but thought it was better to put the info here to keep it all together.

I wanted to expound on the reason why I (and so many others) use a mixture of sand and Eco Earth and other things as Substrate.

The mixture as stated in the original post above is...
4 parts play sand
6 parts Eco Earth or coconut fiber bedding
2 parts worm castings
1 part leaves from deciduous trees

The sand is for good packing ability. It gives the solidness that is needed for firm walls. Too much and your substrate is too dry. Wrong kind of sand, for example calcisand and it can get hard like a rock when it dries and trap a crab underground. Calcisand also when dry and loose is very fine and caves in behind tunneling crabs cutting off their oxygen supply rather quickly. So a course sand is desirable. You also don't want sharp cutting glass like pieces. Coal slag is not recommended. Play sand is most commonly used, as is all purpose sand. They are cheap and have proven to be ideal. It is not good by itself as it does not hold moisture well alone. It needs a little help so we mix it with Eco Earth.
Eco Earth and Forest Bedding are name brands of coconut fiber bedding. It is great for holding moisture and packs loosely allowing the crabs to tunnel at will. However it is really too loose as crabs are vulnerable when molting and need more protection than Eco Earth offers. They are at risk of being discovered by other crabs and being cannibalized. If Eco Earth is used alone it is prone to mold issues. Which then attracts fungus gnats and you have a whole new set of problems. So mix in the sand. The two alone still need a little help. We want to add some beneficial bacteria and some biological matter for them to feed on. So next we add..
Worm castings. Worm castings seem to be the best start for our BB. So we add two parts of this but they need something to feed on besides the coconut fiber, which is good and the sand... which is useless to them. So in goes the leaves, even small sticks and stuff can go in. However you don't want any nasties to go in to your... so far pristine tank... be careful where you pick up your leaves. Nothing from conifers (see post #1 for definition) and no pesticides. You will also want to clean and/or treat your leaves in some way before they go into your tank so that you are comfortable that you are not introducing unwanted guests or bacteria to the tank.
You can soak well in very hot water and then spread on a cookie sheet and put in oven on very low temp until dry. The heat will kill most things. Or your can soak in a salt water solution and then rinse in dechlorinated water. The salt will kill most unwanted guests and mold but probably not bacteria. I do both. Watch carefully and keep the heat low to avoid burning leaves.
I have heard of people who do one or the other or neither. It is up to you.
In the end you just crumble them up and mix them in. You are aiming for a sandcastle consistency to your substrate. The goal is to have a substrate that will hold its moisture content without having to mist it all the time. If you find yours is drying out try putting an airstone in your water dishes to raise the overall humidity in your habitat. If the overall humidity is around 80 then your substrate should stay moist.

Good luck, I hope this helps someone.

Similar Aquarium Threads

  • Locked
The Aquatic Weasel
  • Locked
  • Locked
  • Locked
Top Bottom