Becky works as a biological science technician in endangered species conservation and has a passion for biology and wildlife conservation.
About Hermit Crabs
Hermit crabs are small, cute invertebrates that steal our hearts with a wiggle of their antennae and their fun climbing adventures. And what's not to love about an animal that carries its seashell house around with it?
Unfortunately, these critters are one of the most misunderstood animals in the pet trade and are often incorrectly described as easy, cheap, or "throwaway" pets. In reality, hermit crabs require just as much effort as other pets. If cared for properly, they can live for over 20 years!
Myths and improper husbandry advice abound, but have no fear: This guide will help you sift through all the false information.
Myth: Hermit Crabs Will Drown
In the wild, hermit crabs submerge themselves in the ocean to reproduce. They also have access to both freshwater and saltwater. In captivity, they require that all these needs be met.
- Provide both a freshwater and saltwater pool.
- Tap water is perfectly fine to use as long as it is made safe using a water dechlorinator. The only brand proven to be safe for hermit crabs is Seachem Prime (available in the fish section at most pet stores).
- Saltwater should be mixed using marine aquarium salt. Do not mistakenly use freshwater aquarium salt (yes, this product exists!). The best brand to use is Instant Ocean, and it can be found in the fish section of most pet stores.
- Crabs will not drown in deep water dishes as long as they're able to climb out, and most hobbyists agree that hermies benefit from being able to completely submerge themselves.
But Why Did My Hermit Crab Die in Its Water Dish?
Some pet owners complain that their hermit crabs drowned in the water dish, but this is very unlikely. When a crab is sick, distressed, or dying, the first thing it does is head for the water dish. Many crabs pass away in their water dishes because something else was wrong. They did not drown!
Myth: You Can Put a Hermit Crab in Any Type of Cage (Including Wire Cages)
Hermit crabs are one of the few terrestrial animals who use gills to breathe. Because of this unique anatomical feature, they require an incredibly humid environment to survive. Wire cages simply do not work, and the only enclosure suitable for these animals is an aquarium. Covering the tank with a solid plexiglass lid is the best option, or a screen top can be sealed with plastic wrap.
Tip: If you cannot afford an aquarium, a large plastic storage tote/tub can temporarily be used to house crabs. Also, save up! Stores like Petco routinely have a $1 per gallon sale during which aquariums only cost as much as the amount of water they hold (a 40-gallon tank costs $40, a 20-gallon tank costs $20, etc.).
Myth: Hermit Crabs Thrive in Any Type of Temperature and Humidity
Hermit crabs are tropical critters and heavily rely on the conditions in their environment in order to thrive. They need specific temperature and humidity levels or they will perish.
A warm temperature is best achieved by attaching a reptile heat mat to the the back (not the bottom) of the cage. The goal is to heat the air in the enclosure and not the substrate. In colder households, insulating the outside of the aquarium with a water heater blanket can help maintain the correct temperature.
Temperature requirements vary slightly depending on the species of hermit crab, but this table shows the basics:
At least 80%
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Myth: They Don't Need Much Space
Hermit crabs become stressed when overcrowded. They may be social animals, but they still need to be able to move away from their buddies for some alone time every now and then. In fact, a crab's survival during the molting process depends on it. (In preparation for molting, a healthy crab will seek seclusion by completely burying itself, which keeps it safe from other, potentially hungry, hermit crabs.)
The enclosure needs to provide at least 10 gallons of space per crab. This allows enough room for molting, climbing, eating, sleeping, hiding, and digging. This means a 20-gallon aquarium is the minimum tank size for two hermit crabs.
Myth: Hermit Crabs Only Need a Couple Inches of Sand
Having proper substrate is arguably one of the most important aspects of hermit crab husbandry. Crabs bury themselves when molting and heavily rely on the depth, consistency, and moisture of the substrate in order to survive. Crabs will not do well when only provided a couple inches of sand for substrate. They really, truly need the following:
- Depth: Substrate depth should be at least half the tank's height. However, if the aquarium is shorter than 12 inches, then the substrate should be a minimum of six inches deep. Having deep substrate really is important, as the only way a molting crab can protect itself from other hermit crabs is to hide. If not buried deeply enough, a molting crab risks being dug up by its hungry, cannibalistic friends.
- Materials: The best substrate for a hermie is a mixture of two materials: coconut husk bedding (found in the reptile section at pet stores) and kids' play sand (found at any local hardware store). The coconut husk bedding is an important component because it holds moisture and helps maintain a sandcastle consistency for burrowing. For a proper mixture, it's suggested to use one part coconut husk bedding to every five parts kids' play sand.
Myth: Hermit Crabs Eat Store-Bought Pellets
Crabs will eat almost anything, but not commercial hermit crab diets. The pellets and powders sold in pet stores should be avoided because they contain ingredients harmful to crabs (like copper).
A balanced diet with lots of variety keeps crabs healthy. Calcium-rich food should be provided often, as well as protein and fats.
- Fresh and dried fruits and veggies: apple, bell pepper, jalapeno, pomegranate, berries, mango, papaya, grapes, banana, orange, coconut, kale, lettuce, squash, cucumber, carrot
- Fats: peanut butter, coconut oil, sunflower seeds, almonds
- Proteins: mushrooms, shrimp, fish, meal worms, dead crickets, bloodworms, boiled egg
- Calcium-rich foods: oyster shell, eggshell, shed snakeskin, cuttlebone
- Other: kelp, rice, chia seeds, spirulina, leaf litter, worm castings
Myth: Painted Shells Are Fun and Safe
Hermit crabs are actually quite picky about their shell choices, and they even modify their shell to better suit their needs by chewing the edges and carving out the inside. Because of this, painted shells are toxic to crabs! Ingesting paint isn't safe for us, and it definitely isn't safe for a fragile invertebrate, either.
- At least six appropriately-sized shells should be available at all times for each crab. For example, two crabs require 12 shell choices, three crabs need 18, and four need 24. If hermies are not given enough options, they will fight and may even kill each other.
- Different species of hermit crab tend to prefer different types of shells. Keep this in mind when shopping for shells!
Myth: Hermit Crabs Are Pets You Can Hold
Hermit crabs are not only fragile animals who can suffer major injuries if dropped but, as mentioned earlier, they're creatures who live on land but breathe through gills. Removing a hermit crab from its humid, warm enclosure into a cooler, drier room causes stress, and these animals do not handle stress well.
Myth: They Are Cheap Pets
Now that the common myths have been busted, it becomes quite obvious that providing hermit crabs with the care they need is most definitely NOT cheap. The initial purchase of the enclosure, decor, substrate, water dishes, and food will cost $60–$100, and that doesn't even include the price of the crabs! And as a hermit crab grows, it will require bigger, more expensive shells. Jumbo-sized crabs will eventually require difficult-to-obtain shells that can cost up to $20.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
Emily on July 06, 2020:
Hermit crab girl no they need a totally closed cage with at least 80% humidity and lots of playsand to molt. It should be sandcastle consistency. You should have something plastic over the top and a digital thermometer and digital hygrometer to measure the humidifier and temperature.
Hermit crab girl on June 27, 2020:
So i have had hermit crabs for 2 years and every year they die not even after i have had them for maybe 6 months. I love them dearly and hate to see them go. I just got 2 new ones and idk how i should help them thrive because both are kinda mean lol also idk if the painted rocks that they give u when u first get them r ok to leave them in or should i get rid of them as soon as i get back to my house... Also would a half closed half barred cage work? I dont usually let then have the hermit crab food unless we r out of the food i usually give them some one please help me i would like to see them live
Crab girl on September 08, 2019:
I love crabs they are so cut im going to buy one maybe tommow
HyoJung on December 09, 2018:
Hey I have read so many articles saying orange is not good for hermit crabs but you said it's ok. I don't know what to believe.
Adrian on August 31, 2018:
I just saw one of my crab getting into the shell of my other one. I’m scared he’s gonna die, what do I do?
Jamie on June 27, 2018:
I have a 38 gallon breeders tank and have been raising hermits for years my biggest ones are the size of a softball and are trained like a dog! Boris my favorite loves to eat popcorn in my bed with me while I read! If you are patient and consistent they learn like a dog learns and love their owners ! Each has a distinct personality and likes and dislikes . Very misunderstood and very loyal and trusting . I have raised mine all to be hand feeders and lap pets but also respect the instinct side of them also and work closely with their inbread habits but have been able to manipulate them enough over time to change the way they respond to me and handeling
Paris on June 22, 2018:
I think this will help my hermit crabs a lot.
Stampa on June 18, 2018:
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Rachel on May 27, 2018:
Hi! So I just got hermit crabs a few months ago. Chips and Guacamole. But Chips just died because of his pincher falling off. So I decided to get two more crabs. Thunder and Toasty. But Thunder dug himself under moss and shells and sticks and when I was checking on them I decided to isolate him Incase of any stress levels rising. He ended up losing all of his legs but his pinched then died..
hello on July 31, 2017:
thank u so much. this helps a ton!
Ron on June 11, 2017:
In a terrarium is it safe to have chicken wire on the walls of the tank for the crabs to climb on?
Jay on June 08, 2017:
You can use other types of dechlorinator besides prime; anything that removes chlorine, chloramine and heavy metals are fine.... Depending on size, 2-3 small crabs (size of a golf ball) can do fine in a 10g tank for a few years; and most places recommend a minimum of 5g per crab. And you don't need a 5:1 ratio (sand:EE), hermit crabs do fine with straight sand, straight EE or mix of each, whatever ratio you can think of...
Kala Khan Abbasi on October 02, 2016: