Hermit crabs can nibble a tiny piece of plain dog food now and then, but it is not a good staple. Most dog foods contain preservatives, salt and fats that are not made for crabs, so keepers feed a varied mix of fresh foods and hermit crab food instead. Whatever you feed, your crabs also need dishes of dechlorinated fresh water and marine salt water at all times.
Why Dog Food Is Not a Good Staple
- Preservatives: Many kibbles contain chemical preservatives. Crab keepers generally avoid foods with BHA, BHT, ethoxyquin and copper sulfate.
- Wrong balance: Dog food is balanced for dogs. Hermit crabs need calcium and a mix of plant and animal foods.
- Mold and mess: Moist or soft dog food spoils quickly in a warm, humid tank.
If a crab is hungry and you have nothing else, a small, plain piece of dry kibble with no added colors or seasoning is unlikely to harm it for a day. Remove any uneaten food within a day.
What to Feed Instead
- A good commercial hermit crab food with no added preservatives or dyes as a base.
- Fresh fruit and vegetables such as mango, apple, carrot, sweet potato (cooked) and leafy greens.
- Unsweetened coconut and plain nuts in small amounts.
- Protein such as plain cooked egg, shrimp, fish or dried mealworms a few times a week.
- A cuttlebone or crushed eggshell for calcium.
Avoid onion, garlic, anything salted or seasoned, processed human snacks and foods that contain preservatives. For more ideas, see our guides on types of foods hermit crabs can enjoy and what hermit crabs eat in captivity.
Fresh Water and Salt Water
Hermit crabs use water to drink and to refill their shells, so they need two dishes at all times: one with fresh water and one with salt water. Treat tap water with a dechlorinator, because chlorine and chloramine can harm them. Make the salt water with a marine salt mix, the kind used for saltwater aquariums, rather than table salt. Use shallow dishes with a ramp or sponge so the crabs can climb out without drowning.
Basic Tank Needs
- Keep at least two crabs, since they are social.
- Start with at least a 10-gallon tank for a couple of small crabs; bigger is better.
- Use a deep, damp mix of sand and coconut fiber so crabs can burrow and molt.
- Keep the tank warm and humid, typically around 75 to 85 degrees F and 70 to 80 percent humidity.
This is general information. Hermit crab care has many variables, so ask an exotic-pet vet or an experienced keeper if your crab is not eating or molting.
Bottom Line
Dog food is not poisonous in tiny amounts, but it is not a good choice for hermit crabs. Offer a varied diet of crab food, fresh produce and occasional protein, and always keep fresh and salt water available.
