Crayfish are omnivorous...like most shrimp and lobsters. That means they will eat almost anything. Crayfish eat fish, shrimp, water plants, worms, insects, snails, plankton, and more. They will also eat dead plants and animals. They hold their food with their claws. The amount of food they eat affects how often they molt. When they molt they need to eat their shell to give them calcium. If you can, try to feed your crayfish a water plant called elodea. Leave the elodea in its tank. You can also feed them cat food and hot dogs.