One of the most important question for each hermit crab owner is "What can a hermit crab eat?" As a general rule, these exotic pets are fairly easy to feed. They can survive on almost any commercial hermit crab food that you can buy from your favorite pet shop. Some fish flakes may also be okay, depending on the main ingredients.
You should carefully read labels. Any fish food flakes or pellets hat contain copper sulfate or ethoxyquin may be lethal to your pet. Tocopherols are okay since these are natural preservative found in fish food.
You do have to remember that most land hermit crabs are omnivores, and they are not finicky eaters. Hermit crabs love as much variety of food as possible, starting from all sorts of fresh vegetables and fruits. Make sure that these are freshly washed and patted dry. Vegetable leaves (like those from cabbage, lettuce, and spinach) should be dry and crisp.
Fruits should at least be chopped into manageable pieces and patted dry before serving to your pets. If you like giving them citrus fruits (which these small animals also love) try letting some of the pulp remain on a piece of paper towel first so that the juices do not drip a lot into your pet's enclosure. However, make sure that you do remove leftovers the next day, since these can rot very quickly.
If you want, you can also serve a bit of (unsalted / air popped) popcorn, large pinches of plain bread and even fresh (but washed) tree bark for more variety.
A note of warning though: although hermit crabs are omnivores, it would be best to steer your pets from meat. Any food that contains meat can become toxic. Fish meat is okay as long as it if fresh and not from an already processed dish. Raw fish meat or any type of seafood is also okay, especially if you can spare a slice of sushi (tuna) or two. Also try not to give your pet anything that contains too salt or sugar. Junk food like potato chips and doughnuts should not be introduced to your pet at all.
Remember to always provide fresh clean drinking water in a shallow dish in their crabitat. You should replace this water about twice a day.