In-Depth Hermit Crab Care Guide
By Leah Klingelheber
Intro
This is OHCR's in-depth land hermit crab care guide. This is where I bore you with every single little detail that we know about crabs. This is where I recommend specific products and give the reasons we do things the way we do. This care guide includes pictures, links to websites, and product recommendations.
I would make a bibliography, but it would have to include every possible hermit crab-mentioning source on the internet, because I’ve read them all. Probably more than once. I can’t remember all of the sources I’ve used over the years, or where I got my information. Plenty of it is stuff I’ve figured out myself and plenty is repeated numbers and info I have seen written over and over. I can’t name every site that has helped me in my crabbing life, so I’ll just give the big one: The Hermit Crab Association. Especially it’s forums. I very highly recommend it for all of your crabby questions.
One more note: this care guide is mainly for purple pincher aka Caribbean hermit crabs, the most common type sold as a pet. Ecuadorians are the second most popular and have nearly identical requirements as PPs. Other species such as strawberry hermit crabs and viola hermit crabs may have some different needs than what is stated here. I cannot write much about the other species as we've never had any, only PPs and Es.
Contents
Tank Size
Number of Crabs
The Tank Itself
Substrate
Humidity
Temperature
Lighting
Water
Food
Shells
Habitat Decor
Handling
Cleaning
Tank Size
10 gallon aquariums are everywhere. Tank size for a gerbil? 10 gallons. Fish? 10 gallons. Hamster? 10 gallons. Hermit crab? 10 gallons. 10 gallons, 10 gallons, 10 gallons, 10 gallons.
I’m here to tell you to ditch 10 gallons. 10 gallons is TOO SMALL! For hamsters, gerbils, reptiles, hermit crabs-- it’s too small. (Fish are arguable, depending on species). 10 gallons has been the staple for as long as I can remember. I used to have 10g aquariums. I kept my crabs in one at one point, but I think as a pet-keeping world we should break the standard of 10 gallons.
Yes, I know that the HCA states 10g as the minimum tank size for hermit crabs, and so do many other sources. We feel differently. With all of the things that hermit crabs need, a tank that small gets crowded. Crabs need space to tunnel and climb and forage. Not to mention room for friends. There’s not much space for that left once you add in all the necessities. A 20 gallon minimum is the size we recommend for any crab. As with any animal, the more space the better. 40 gallon ‘breeder’ style tanks are wonderful for hermits, providing lots of floor space. 55g aquariums are usually longer and taller, and are also a great choice. There is no size that is ‘too big’. In their original home in the wild, hermit crabs have miles of beaches and forests. They are migrators. 10 gallons isn’t going to cut it.
Number of Crabs
So how many hermits can 20 gallons hold? 2 or 3, 4 tops. The size of crabs doesn’t matter much, because younger and smaller crabs cover just as much space when they come out at night. A general rule to follow is 3 crabs for the first 20 gallons, then one crab for each additional 5 gallons.
Never have only one crab. If you find yourself with a single hermit, try to adopt another one as soon as possible. They are social animals that thrive in the company of others. A lonely crab will become stressed and sad. Stress in small animals is a key cause of death. The more crabs the merrier! (Provided there is space for them).
When adding a new crab to the tank, usually they can be plopped in there without a hitch and will get along great with the others. If you suspect the new crab might be sick or otherwise not fit for company just yet, quarantine it in a smaller tank (10 gallons is a good size this time) until you think it's safe to introduce it.
The Tank Itself
Tanks are all pretty uniform-- a glass or acrylic box. What’s important is what you cover it with. If you have a mesh lid, you’ll need to cover most of it with something like plastic wrap to keep the humidity in. That is what we do. Whatever covers your tank, just make sure the inhabitants can breathe, meaning they need air and humidity, and that they can’t escape. The lid also needs to be heavy enough so that if the crabs push up on it they can't get out.
Substrate
Everywhere you look (crab-related) you’ll see “Eco Earth”. Yes, Eco Earth is great, and perfect for hermit crabs. Ha, bet you thought I was about to shame Eco Earth too. When using Eco Earth, it’s most practical to buy the compressed blocks that you add water to instead of the loose bags. It’s cheaper, for one, and once you mix it up it’s already nice and moist. Eco Earth is not the only coconut fiber substrate you can use for your crabs. I like to also use one called Plantation Soil. It’s cheaper than Eco Earth from Amazon.
Coconut substrate by itself is good, coconut mixed with quality sand is better. I won’t specify a ratio, because really any works. Some people prefer mostly sand, and some always use exactly half and half. Ours is about half and half, if not more coconut fiber. Many people use play sand for their crabs. We haven’t found a great brand around here like other’s have. Instead we use aquarium sand. A good brand for crabs is Super Naturals. But if you can find a quality play sand, use that, it’ll be cheaper.
Substrate should be at least 5 inches. This is because hermit crabs burrow underground to molt, and also they just enjoy digging. I would only recommend adding more inches of substrate if you have a tank that is tall rather than wide. Too much substrate in shorter tanks takes away from climbing room.
Humidity
Hermit crabs, even the ones that live on land, use gills to breathe. Many of the deaths of crabs that are in captivity are due to suffocation. Not from lack of air, but from lack of water. The aquarium must be humid so that the crabs are taking in a sufficient amount of water with their air. When measured, humidity should be around 75-80%. Without measuring, the substrate should stay moist (but not dripping when squeezed). Good buffers for humidity are spraying the tank with fresh water, moss, and foggers and bubblers.
Temperature
Caribbean (purple pincher) hermit crabs come from-- guess where-- the Caribbean! And the Caribbean is warm. Unless the inside of your house maintains tropical heat, your hermits will need a heater. Heat lamps are NOT a good option, as they dry out the air and substrate in the tank. The best way to heat the crabitat is with an under tank reptile heater. The heater(s) are not to be placed under the tank as with most animals, but stuck on the side. This is because below all of that substrate it won’t actually heat the air, and will only dry out that patch of substrate. The heater(s) can be put on one side of the tank or both. The actual temperature of the tank needs to be between 72 and 80 degrees. Ideally, one side should be on the cool side and one side warmer.
Lighting
Hermit crabs don’t need artificial lighting. A room with windows is just fine. Since heat lamps don’t work, the only reason you would want a light is for aesthetic purposes, or plants if you dare to try that. Personally I like LED lights the best for viewing tanks and aquariums, especially ones with a blue night light for nocturnal viewing.
Water
If you’ve even glanced at any other care source, you’ll know that hermit crabs require both fresh and saltwater. In the wild, land hermits have access to the oceans and the streams and rivers that run into it. I’ve been to the gulf of mexico and found hundreds of crabs on the shore of an estuary, the spot where a river meets the sea. Both water sources should be dechlorinated. You could also just let it sit for a week or so, I find that works too. At least one of the bowls needs to be deep enough for your biggest crab to fully submerge (but the little ones still need a way out!), ideally both bowls are pretty big.
To make saltwater, we use salt meant for marine aquariums. The easiest way is to mix it up one gallon at a time in a milk jug or something similar. I use the brand Instant Ocean, and find that it works very well. DO NOT use any kind or at brand of table salt. They contain iodine which is very toxic to crabs and will kill them. A rule of thumb is if it's questionable, don't use it; it’s better safe than sorry.
Food
Wild hermits are big time scavengers. They will eat basically anything. The best diet is a large variety of fruits, vegetables, meats, nuts, and some grains. My crabs really like carrots, peanuts, and krill. Foods can be fresh or dried. My favorite feed is the variety pack from the ebay store, Hugs for Hermits. It comes with all of the food groups, and there is so much variety. Every time I order from her it’s a slightly different mix, so our crabs get lots of different foods. Other stores with good food are Alaska Hermit and some stores on Etsy. Really just feed your crabs a balanced diet, sort of like a human diet, but with smaller and healthier proportions.
There are lists you can find on the internet of safe and not-safe foods for your crabs. In general, don’t feed them citrus fruits, anything processed, or commercial foods. Really anything else is crab safe, but if you aren’t sure, look it up! Always try to remove food before it molds. Dried foods might last more than one night, but fresh food tends to get gross after 24 hours.
Shells
Some hermits won’t switch shells until they’re falling out of the one they are in, while others hop from home to home once a month. Sometimes when one crab changes, a chain reaction is unleashed and suddenly all of your crabs are in new shells. Because shells don’t grow with their inhabitants, it is important that hermit crabs always have a variety to choose from. Most Caribbean hermit crabs prefer shells with smooth, round openings. Turbo shells and magpie shells are perfect. I love buying shells from Richard's Seashells online store, they are always beautiful. There should be multiple good-fitting options for each crab, which can be overlapping among crabs. Occasionally I like to clean all of the shells I keep in the tank by boiling them for a couple minutes. It’s also good to do this with new shells.
Hermit crab shells are measured by the width of the opening. Buy shells that are about the same and bigger than the size they are currently in.
Obviously I’m going to tell you to not use painted shells. They irritate the crabs’ body, can poison them if they chip off and eat it, and the crabs are forced into these ugly shells after being taken from the wild. They aren’t a good idea, please don’t do it.
Habitat Decor
Hermit crabs are explorers. They love to climb and can be very active. Fake plants and vines work wonderfully in the crabitat, and so does driftwood. Other great decorations include cholla wood, caves/hides, plastic shower caddies, hemp nets, and cork structures. It is good to have climbing options reaching all of the way to the top of the tank. If you have a mesh lid the crabs will love to climb on that too.
Handling
Hermit crabs are not meant to be handled, but admired and respected from a distance. When you do occasionally need to pick up your crab, pick it up by it’s shell and set it in your hand. Handling can be very stressful for hermits, and stress in small animals can cause other issues. Make sure to keep your hand flat and try not to scare them. They do have punchers and they might pinch! If they do pinch, it is best to stay calm and relax your hand as best as you can. The crab will let go a lot faster if you aren't flinging your hand around.
Cleaning
Luckily after you’ve spent all of that time and money setting up your crabs’ habitat, you don’t have to work on it much after that. Water bowls need to be changed as needed, and food should be taken out before it rots. Other than that and occasional spot cleaning poop there’s not much to do.
I completely clean out my crabitat with new substrate and all only once or twice a year, though you need to clean and sterilize everything immediately if your tank gets a bug or parasite infestation or your crabs get a disease. If this happens, throw out the substrate (it’s too much of a pain to clean it) and boil all of the non-plastic decorations. Wood can be soaked for a few days or baked at about 250 degrees for a couple of hours. The tank and decorations you don’t want to boil should be sterilized with a vinegar-water solution and rinsed thoroughly after.
If your hermits get mites (very common tiny white parasites) or another parasite or disease they can be soaked in spring water for a few minutes. The water can be deep with a way for the crabs to get onto land or shallow so that they aren’t submerged.
This is OHCR's in-depth land hermit crab care guide. This is where I bore you with every single little detail that we know about crabs. This is where I recommend specific products and give the reasons we do things the way we do. This care guide includes pictures, links to websites, and product recommendations.
I would make a bibliography, but it would have to include every possible hermit crab-mentioning source on the internet, because I’ve read them all. Probably more than once. I can’t remember all of the sources I’ve used over the years, or where I got my information. Plenty of it is stuff I’ve figured out myself and plenty is repeated numbers and info I have seen written over and over. I can’t name every site that has helped me in my crabbing life, so I’ll just give the big one: The Hermit Crab Association. Especially it’s forums. I very highly recommend it for all of your crabby questions.
One more note: this care guide is mainly for purple pincher aka Caribbean hermit crabs, the most common type sold as a pet. Ecuadorians are the second most popular and have nearly identical requirements as PPs. Other species such as strawberry hermit crabs and viola hermit crabs may have some different needs than what is stated here. I cannot write much about the other species as we've never had any, only PPs and Es.
Contents
Tank Size
Number of Crabs
The Tank Itself
Substrate
Humidity
Temperature
Lighting
Water
Food
Shells
Habitat Decor
Handling
Cleaning
Tank Size
10 gallon aquariums are everywhere. Tank size for a gerbil? 10 gallons. Fish? 10 gallons. Hamster? 10 gallons. Hermit crab? 10 gallons. 10 gallons, 10 gallons, 10 gallons, 10 gallons.
I’m here to tell you to ditch 10 gallons. 10 gallons is TOO SMALL! For hamsters, gerbils, reptiles, hermit crabs-- it’s too small. (Fish are arguable, depending on species). 10 gallons has been the staple for as long as I can remember. I used to have 10g aquariums. I kept my crabs in one at one point, but I think as a pet-keeping world we should break the standard of 10 gallons.
Yes, I know that the HCA states 10g as the minimum tank size for hermit crabs, and so do many other sources. We feel differently. With all of the things that hermit crabs need, a tank that small gets crowded. Crabs need space to tunnel and climb and forage. Not to mention room for friends. There’s not much space for that left once you add in all the necessities. A 20 gallon minimum is the size we recommend for any crab. As with any animal, the more space the better. 40 gallon ‘breeder’ style tanks are wonderful for hermits, providing lots of floor space. 55g aquariums are usually longer and taller, and are also a great choice. There is no size that is ‘too big’. In their original home in the wild, hermit crabs have miles of beaches and forests. They are migrators. 10 gallons isn’t going to cut it.
Number of Crabs
So how many hermits can 20 gallons hold? 2 or 3, 4 tops. The size of crabs doesn’t matter much, because younger and smaller crabs cover just as much space when they come out at night. A general rule to follow is 3 crabs for the first 20 gallons, then one crab for each additional 5 gallons.
Never have only one crab. If you find yourself with a single hermit, try to adopt another one as soon as possible. They are social animals that thrive in the company of others. A lonely crab will become stressed and sad. Stress in small animals is a key cause of death. The more crabs the merrier! (Provided there is space for them).
When adding a new crab to the tank, usually they can be plopped in there without a hitch and will get along great with the others. If you suspect the new crab might be sick or otherwise not fit for company just yet, quarantine it in a smaller tank (10 gallons is a good size this time) until you think it's safe to introduce it.
The Tank Itself
Tanks are all pretty uniform-- a glass or acrylic box. What’s important is what you cover it with. If you have a mesh lid, you’ll need to cover most of it with something like plastic wrap to keep the humidity in. That is what we do. Whatever covers your tank, just make sure the inhabitants can breathe, meaning they need air and humidity, and that they can’t escape. The lid also needs to be heavy enough so that if the crabs push up on it they can't get out.
Substrate
Everywhere you look (crab-related) you’ll see “Eco Earth”. Yes, Eco Earth is great, and perfect for hermit crabs. Ha, bet you thought I was about to shame Eco Earth too. When using Eco Earth, it’s most practical to buy the compressed blocks that you add water to instead of the loose bags. It’s cheaper, for one, and once you mix it up it’s already nice and moist. Eco Earth is not the only coconut fiber substrate you can use for your crabs. I like to also use one called Plantation Soil. It’s cheaper than Eco Earth from Amazon.
Coconut substrate by itself is good, coconut mixed with quality sand is better. I won’t specify a ratio, because really any works. Some people prefer mostly sand, and some always use exactly half and half. Ours is about half and half, if not more coconut fiber. Many people use play sand for their crabs. We haven’t found a great brand around here like other’s have. Instead we use aquarium sand. A good brand for crabs is Super Naturals. But if you can find a quality play sand, use that, it’ll be cheaper.
Substrate should be at least 5 inches. This is because hermit crabs burrow underground to molt, and also they just enjoy digging. I would only recommend adding more inches of substrate if you have a tank that is tall rather than wide. Too much substrate in shorter tanks takes away from climbing room.
Humidity
Hermit crabs, even the ones that live on land, use gills to breathe. Many of the deaths of crabs that are in captivity are due to suffocation. Not from lack of air, but from lack of water. The aquarium must be humid so that the crabs are taking in a sufficient amount of water with their air. When measured, humidity should be around 75-80%. Without measuring, the substrate should stay moist (but not dripping when squeezed). Good buffers for humidity are spraying the tank with fresh water, moss, and foggers and bubblers.
Temperature
Caribbean (purple pincher) hermit crabs come from-- guess where-- the Caribbean! And the Caribbean is warm. Unless the inside of your house maintains tropical heat, your hermits will need a heater. Heat lamps are NOT a good option, as they dry out the air and substrate in the tank. The best way to heat the crabitat is with an under tank reptile heater. The heater(s) are not to be placed under the tank as with most animals, but stuck on the side. This is because below all of that substrate it won’t actually heat the air, and will only dry out that patch of substrate. The heater(s) can be put on one side of the tank or both. The actual temperature of the tank needs to be between 72 and 80 degrees. Ideally, one side should be on the cool side and one side warmer.
Lighting
Hermit crabs don’t need artificial lighting. A room with windows is just fine. Since heat lamps don’t work, the only reason you would want a light is for aesthetic purposes, or plants if you dare to try that. Personally I like LED lights the best for viewing tanks and aquariums, especially ones with a blue night light for nocturnal viewing.
Water
If you’ve even glanced at any other care source, you’ll know that hermit crabs require both fresh and saltwater. In the wild, land hermits have access to the oceans and the streams and rivers that run into it. I’ve been to the gulf of mexico and found hundreds of crabs on the shore of an estuary, the spot where a river meets the sea. Both water sources should be dechlorinated. You could also just let it sit for a week or so, I find that works too. At least one of the bowls needs to be deep enough for your biggest crab to fully submerge (but the little ones still need a way out!), ideally both bowls are pretty big.
To make saltwater, we use salt meant for marine aquariums. The easiest way is to mix it up one gallon at a time in a milk jug or something similar. I use the brand Instant Ocean, and find that it works very well. DO NOT use any kind or at brand of table salt. They contain iodine which is very toxic to crabs and will kill them. A rule of thumb is if it's questionable, don't use it; it’s better safe than sorry.
Food
Wild hermits are big time scavengers. They will eat basically anything. The best diet is a large variety of fruits, vegetables, meats, nuts, and some grains. My crabs really like carrots, peanuts, and krill. Foods can be fresh or dried. My favorite feed is the variety pack from the ebay store, Hugs for Hermits. It comes with all of the food groups, and there is so much variety. Every time I order from her it’s a slightly different mix, so our crabs get lots of different foods. Other stores with good food are Alaska Hermit and some stores on Etsy. Really just feed your crabs a balanced diet, sort of like a human diet, but with smaller and healthier proportions.
There are lists you can find on the internet of safe and not-safe foods for your crabs. In general, don’t feed them citrus fruits, anything processed, or commercial foods. Really anything else is crab safe, but if you aren’t sure, look it up! Always try to remove food before it molds. Dried foods might last more than one night, but fresh food tends to get gross after 24 hours.
Shells
Some hermits won’t switch shells until they’re falling out of the one they are in, while others hop from home to home once a month. Sometimes when one crab changes, a chain reaction is unleashed and suddenly all of your crabs are in new shells. Because shells don’t grow with their inhabitants, it is important that hermit crabs always have a variety to choose from. Most Caribbean hermit crabs prefer shells with smooth, round openings. Turbo shells and magpie shells are perfect. I love buying shells from Richard's Seashells online store, they are always beautiful. There should be multiple good-fitting options for each crab, which can be overlapping among crabs. Occasionally I like to clean all of the shells I keep in the tank by boiling them for a couple minutes. It’s also good to do this with new shells.
Hermit crab shells are measured by the width of the opening. Buy shells that are about the same and bigger than the size they are currently in.
Obviously I’m going to tell you to not use painted shells. They irritate the crabs’ body, can poison them if they chip off and eat it, and the crabs are forced into these ugly shells after being taken from the wild. They aren’t a good idea, please don’t do it.
Habitat Decor
Hermit crabs are explorers. They love to climb and can be very active. Fake plants and vines work wonderfully in the crabitat, and so does driftwood. Other great decorations include cholla wood, caves/hides, plastic shower caddies, hemp nets, and cork structures. It is good to have climbing options reaching all of the way to the top of the tank. If you have a mesh lid the crabs will love to climb on that too.
Handling
Hermit crabs are not meant to be handled, but admired and respected from a distance. When you do occasionally need to pick up your crab, pick it up by it’s shell and set it in your hand. Handling can be very stressful for hermits, and stress in small animals can cause other issues. Make sure to keep your hand flat and try not to scare them. They do have punchers and they might pinch! If they do pinch, it is best to stay calm and relax your hand as best as you can. The crab will let go a lot faster if you aren't flinging your hand around.
Cleaning
Luckily after you’ve spent all of that time and money setting up your crabs’ habitat, you don’t have to work on it much after that. Water bowls need to be changed as needed, and food should be taken out before it rots. Other than that and occasional spot cleaning poop there’s not much to do.
I completely clean out my crabitat with new substrate and all only once or twice a year, though you need to clean and sterilize everything immediately if your tank gets a bug or parasite infestation or your crabs get a disease. If this happens, throw out the substrate (it’s too much of a pain to clean it) and boil all of the non-plastic decorations. Wood can be soaked for a few days or baked at about 250 degrees for a couple of hours. The tank and decorations you don’t want to boil should be sterilized with a vinegar-water solution and rinsed thoroughly after.
If your hermits get mites (very common tiny white parasites) or another parasite or disease they can be soaked in spring water for a few minutes. The water can be deep with a way for the crabs to get onto land or shallow so that they aren’t submerged.