In the wild, hermit crabs are scavengers. Because of this, they are “hard wired” to search out the widest variety of foods possible. Their natural diet includes plants, meat, fish, seaweeds, and even fecal matter.
Because they search out such a variety of foods, hobbyists now believe that land hermit crabs will simply choose not to eat anything rather than filling up on food that they’ve already eaten once in the past several hours, so it’s important to offer a variety of foods, if not at once, at least day to day.
Pet stores offer a variety of commercial foods to feed your hermit crabs. I highly recommend picking up one or two of these to rotate in your food dish day after day. However, when choosing a hermit crab food, it is important to be aware of the ingredients. There are some ingredients that are frequently found in commercial hermit crab foods that many believe are harmful to the hermit crabs in the long term. Two of the biggest “offenders” are ethoxyquin and copper sulfate, both of which are found in pesticides.
While land hermit crabs are not insects, their crustacean physiology is similar enough that many do not feel comfortable feeding foods with these ingredients. While I do not completely avoid foods that contain these ingredients, I do try to feed them less often. Each crab owner needs to take a look at the possible dangers and make a judgment call about how often, if at all, they feel comfortable feeding their crabs food that may contain these substances. For more information about the harmful substances sometimes found in commercial pet foods, click here.
The best commercial foods currently available are:
I especially want to recommend Julia Crab’s Epicurean Hermit Crab Cuisine. While it’s a little more expensive and must be ordered online, Julia Crab has done and is doing extensive research on the diet of the land hermit crab, and has concocted the most completely nutritious dry hermit crab food currently available from organic and chemical free human grade foods.
One other caveat about commercial foods is that many of them come in a large, hard pellet form. This style of food can be difficult for crabs to get their claws around, especially if you have smaller crabs or crabs missing their big pincher. If the food you decide to buy is this style, remember to crush it before serving.
Much ado is made in the online hermit crab community about how feeding commercial pet foods to your hermit crabs is completely bad because so many commercial foods contain questionable ingredients.
While I recognize that it is hard to find a good, complete hermit crab diet commercially, that doesn’t mean the pet store should be completely discounted. There is a lot there that can be used to supplement your hermit crabs’ diets beautifully, especially if what seems most difficult about feeding your crabs a fresh or even dry homemade diet is finding your hermit crabs a good protein source.
The Aquatic Freezer
Most large pet stores have a small freezer near their aquarium section where you can buy frozen fish foods. Almost all of these are acceptable for your hermit crabs to eat – frozen blood worms, shrimp, krill, silversides, even plankton. This is also where you’ll find blister packs of frozen Marine Cuisine, which are hermit crab friendly and can be popped out of the freezer into a food dish and once it thaws out it’s a nice stinky treat for your hermit crabs.
Freeze Dried Foods
Also found in the fish and reptile areas are lots of different kinds of freeze dried foods that have no other preservatives or additives, which make a great addition to a dry homemade food. Almost everything you can find frozen in the aquatic section you can also find freeze dried, along with things like mealworms and crickets from the reptile section of the store. They may not look yummy to you, but your hermit crabs will love them!
The Avian Section
While birds and hermit crabs don’t have a lot in common, a few birding necessities are great for hermit crabs. Cuttlebone is probably the best example of an item found commonly in both a bird cage and a hermit crab tank. Cuttlebone is the calcium rich bone of a cuttlefish, and once crushed into manageable chunks, it makes a great calcium supplement.
Another wonderful thing I’ve found in the avian section of the pet store are KayTee Healthy Toppings. They are little pouches of dried fruits, nuts, and vegetables, which hermit crabs love. Bulk bird seed is another idea for a dietary supplement. You can buy just an ounce of bird seed, and often they will have a hermit crab friendly mix of seeds and grains available.
There are also other options if you don’t like the idea of serving your crab any of the available commercial foods, or if you just run out and can’t get to the store for more right away.
Homemade Dry Crab Food
Most commercial foods are “dry” powders or pellets. You can make something similar at home as well. The basic building block of a crustacean’s diet are lipids, proteins, and carbohydrates.
Proteins: For dry food, unsalted ground nuts are probably the easiest to procure, though ground dried fish would be even better, from the crab’s perspective. Occasionally, you can find acceptable dried fish in the cat and dog treats a section of the pet store.
Lipids: fats, foods that contain this include coconut (which can be found in dried, unsweetened form for your crabs) and oily seeds like the sunflower seed (unsalted).
Carbohydrates: Grains such as flax seed, oats (not instant), and brown rice as well as fruits can be added for carbohydrates.
If you use these basic building blocks, you should come up with a fairly complete crab food, especially if you supplement it occasionally with fresh/thawed fruit or fresh/thawed fish.
One thing you may wish to include directly in a dry food is a calcium supplement. Especially when crabs are pre- or post- molt, calcium is incredibly important to their ability to harden their new exoskeleton. Plain powdered calcium carbonate is a good calcium source, as are powdered oyster shells and egg shells (though these may spoil quickly if the membrane isn’t completely removed), and green leafy vegetables.
Powdered or crushed seaweed of some sort is also beneficial to crabs because it is such an essential part of their diet in the wild. This can be obtained either at grocery stores (check near sushi ingredients) or they can be found in the fish section of aquarium or pet stores.
One alga that is very beneficial to crabs is spirulina, which is often sold as a supplement at health food stores. Color enhancing fish flakes also often contain at least some spirulina, but most also contain less desirable ingredients like ethoxyquin as well.
Hermit crabs also enjoy fresh supplements to their diet. They can be fed a lot of things, though staying away from processed, sugary, or salty foods is probably best for your crabs. More often than not, they can be fed unseasoned foods from your table, such as fish or chicken, most fruits, most vegetables, eggs… the list is pretty long.
In our habitat, fresh fish, shredded carrots, raisins, and coconut (especially fresh coconut) seem to be some of the biggest hits.
They can also be fed many kinds of flower blossoms and tree leaves, assuming no pesticides have recently been used on them. Carotenoids, including beta carotene, are an important part of their nutrition and help them to brighten or darken their colors, as can shrimp (unshelled), krill, and tannins from things like dried oak leaves and bark. To improve color in hermit crabs, these foods should be fed consistently for some time before a molt.
Because hermit crabs are scavengers in the wild, many hermit crab enthusiasts believe they liked their food a little “old” and broken down. Fruit that has gotten over ripe, fish that’s been left out just a little too long, and thawed frozen fruits/fish seem to go over really well, probably due to the breakdown in cellular structure that begins to happen when food gets a little old (or when it freezes).
Often hermit crabs will eat better from a fresh dish once the ingredients are a little old, so many people leave fresh food in for more than one day. Pet hermit crabs are kept in an enclosed environment where it is very easy for bacteria to run rampant though, so how long they are comfortable leaving fresh foods in the habitat is something each crab owner should think about.
Remember when taking food out of your tank to check for signs that bits of it may have been dragged off somewhere and clean those up. Hermit crabs will sometimes take food back to their favorite hiding spot, or bury it for later.
The color of a land hermit crab is determined by its access to proper nutrition, sunlight, and, of course, its species. Some of the most important things that a crab can eat to improve its color are tannins and carotenoids.
Tannins can be found in things like oak bark and oak leaves as well as grapes and raisins. Carotenoids are a group of pigments that occur naturally in foods we eat every day.
When processed by land hermit crabs and other crustaceans, they help both to improve their natural color and to regulate their body systems. Read more about carotenoids and the foods that contain them here and here.
Cooking for hermit crabs
Yes, hermit crabs eat cooked food too. You can bake, boil or even fry foods for your hermit crabs provided you use hermit crab safe foods. Common cooking oils that are acceptable for use in hermit crab cuisine are olive oil and coconut oil.
Be creative! This isn’t something I’ve experimented with very much, as I have served our crabs raw fresh foods in the past. I barely cook for the humans in this family!
One recipe I made when my crabs were molting is Coco-Shrimp Scampi. I heated a tablespoon of coconut oil in a frying pan and sauteed a shrimp for a few minutes.
When I was finished, I arranged it on a shell with a generous sprinkling of dried, unsweetened coconut. It was a definite hit. The tail exo bits, especially, were dragged around the tank.
For more information about creating hermit crab cuisine, I recommend visiting Julia Crab at the Epicurean Hermit forum.
Pre- and Post- Molt foods
Especially important pre- and post- molt are calcium rich foods. If they are not made available any other time, when you notice pre molt symptoms or start seeing a crab that’s been down for a molt back up again, bring out the calcium.
This can come in many forms, but most popular among crabbers seem to be cuttlebone (they sell this in the bird section of the pet store), crushed oyster shells, sand dollars, and seafood (like shrimp) that has an exoskeleton still attached.
The only time our crabs get shrimp is when they come up from a molt, as I don’t feel like I can justify the expense except in special circumstances, but I think it’s pretty important for them to get regular calcium supplements, whether that comes from their commercial food, cuttlebone, or a pinch of calcium carbonate mixed with their food.