Hermit crabs are omnivores that eat a surprisingly wide range of foods, from fresh fruits and vegetables to seafood, nuts, seeds, and even dried leaves. In the wild, they scavenge on decaying plant matter, fallen fruit, and animal protein along shorelines, so a varied diet at home keeps them healthiest. The key is offering a rotating mix of plant and animal foods while avoiding a few specific toxic ingredients.
Fruits and Vegetables
Fresh produce should make up a large portion of what you offer. Safe fruits include apples, bananas, blueberries, mangoes, papayas, grapes, coconut, raspberries, blackberries, cherries, peaches, pears, pineapple, cantaloupe, kiwi, figs, pomegranate, and watermelon. Avocado is also safe for hermit crabs, unlike for many other pets.
For vegetables, good options include carrots (including the tops), broccoli, spinach, kale, chard, sweet potato, pumpkin, squash, zucchini, bell peppers, peas, snap beans, celery, beets, asparagus, cauliflower, cabbage, bok choy, and arugula. Dark leafy greens are especially valuable. Avoid iceberg lettuce since it has almost no nutritional value.
Wash all produce thoroughly to remove pesticides, or use organic when possible. You can serve fruits and vegetables raw, and most hermit crabs prefer them slightly soft or starting to brown. Small pieces are easier for them to eat with their tiny claws.
Protein Sources
Hermit crabs need regular animal protein, especially around molting time. Safe options include dried shrimp, dried krill, freeze-dried bloodworms, raw or cooked fish (unseasoned), cooked chicken or egg (no oil, butter, or seasoning), and mealworms. Seafood is a natural favorite since it mirrors what they forage on in the wild.
Plant-based proteins also work well: lentils, chickpeas, beans, soy beans, flax seed, wheat germ, millet, and alfalfa hay all provide protein without animal sources. Offering a mix of both animal and plant proteins a few times per week gives your crabs the amino acids they need for healthy molting and growth.
Calcium for Exoskeleton Health
Calcium is critical for hermit crabs. Without enough, they struggle to form a strong new exoskeleton after molting. The easiest way to provide it is keeping a piece of cuttlebone in the tank at all times. Crabs will nibble on it as needed.
Other calcium-rich foods include crushed eggshells (boiled and dried first), oyster shell, broccoli, dark cooked greens, figs, okra, beans, blackstrap molasses, nuts, and microalgae like spirulina. You can also leave old exoskeletons in the tank after a molt. Crabs almost always eat their shed exoskeleton to recycle the calcium.
Nuts, Seeds, and Healthy Fats
Raw, unsalted nuts and seeds are excellent energy-dense treats. Walnuts, almonds, cashews, pumpkin seeds, sunflower seeds, chia seeds, and flax seeds all work. Coconut, whether fresh, dried (unsweetened), or as unrefined coconut oil, is a hermit crab favorite and provides healthy fats that support their energy levels. The key rule: everything must be raw and free of salt, seasoning, or other additives.
Dried Leaves and Natural Forage
Dried leaves serve double duty as food and enrichment. Hermit crabs love rummaging through leaf litter and slowly eating it over days. Oak and maple leaves are the most popular and easiest to identify safely. Grape leaves, raspberry leaves, and dandelion greens also work well. Some keepers add carrot tops, beet tops, and rose or lilac leaves for variety.
Indian almond leaves (sometimes sold as catappa leaves in pet stores) are another common choice. You can collect leaves yourself as long as the trees haven’t been treated with pesticides or herbicides. Let them dry completely before adding them to the enclosure.
Seaweed and Marine Foods
Seaweed and marine algae are natural parts of a hermit crab’s diet and provide trace minerals they can’t easily get elsewhere. Dried seaweed varieties like nori, arame, and kelp are all safe. Spirulina, a type of microalgae, is particularly rich in carotenoids and protein. Look for plain, unseasoned varieties without added oils.
Foods That Boost Color
If your hermit crab looks pale or washed out, its diet may be lacking carotenoids, the pigments responsible for vibrant orange and red coloring. Foods high in beta-carotene include carrots, red bell peppers, pumpkin, sweet potato, papaya, mango, cantaloupe, apricots, and spinach. Spirulina and other seaweeds are also rich sources.
Tannins contribute to color as well. Dried oak or sycamore leaves and raisins provide tannins naturally. Offering these foods regularly, especially in the weeks before and after molting, helps crabs maintain rich coloring.
Foods and Ingredients to Avoid
A few things are genuinely dangerous for hermit crabs. The two most important ingredients to avoid are copper sulfate and ethoxyquin. Copper compounds are lethal to invertebrates even at low levels, and ethoxyquin is a synthetic preservative toxic to them as well. Both appear frequently in commercial hermit crab pellets and fish-based pet foods. Ethoxyquin is particularly sneaky because it can be present inside fish meal or other composite ingredients without being listed separately on the label.
Beyond those, avoid:
- Table salt: Contains synthetic iodine, which is toxic to hermit crabs. Natural iodine from seaweed and sea salt mixes is fine and actually essential.
- Heavily processed foods: Anything with artificial preservatives, flavorings, or added chemicals.
- Pesticide-treated produce: Wash everything thoroughly or buy organic.
Many experienced keepers avoid most commercial hermit crab food entirely because the ingredient labels lack transparency. If you do use a commercial food, read the label carefully and reject anything containing copper sulfate or ethoxyquin in any form.
Water Matters Too
Hermit crabs need two water dishes: one with dechlorinated fresh water and one with dechlorinated saltwater. Both should be deep enough for the crabs to submerge and fill their shells but easy to climb out of. For saltwater, use a marine salt mix (not table salt) at a specific gravity between 1.020 and 1.025, which mimics natural ocean water. A hydrometer from a pet store lets you check the concentration.
The crabs use these two water sources to regulate the salinity of the water they carry inside their shells. As long as both dishes are available, they’ll adjust on their own.
How Often and How Much to Feed
Feed your hermit crabs once daily, in the evening. They’re nocturnal, so they do most of their eating at night. Remove uneaten food the following morning to prevent mold and fruit flies. You don’t need large portions. A small dish with a pinch of protein, a piece or two of fruit or vegetable, and some dry foods like leaf litter or cuttlebone available at all times is plenty.
Variety matters more than quantity. Rotate what you offer so your crabs get a broad spectrum of nutrients over the course of each week. Many keepers notice their crabs ignore a food one week and devour it the next, so don’t assume a food is rejected permanently after one try. Hermit crabs are foragers by nature, and a changing menu keeps them active and engaged.