Answer:
Crabs will eat pretty much anything that fish will eat. Best choices for food would be Algae Wafers and sinking pellets. They especially love shrimp. Shrimp pellets are an excellent choice. It's not a matter of what kind of food you feed them, but rather, the quality of food you feed them. If you really want your crabs in optimal health, feed them the best brands. A good, high-quality brand you often find in pet stores is Hikari. Other brands like Nutrafin (Hagen), and Tetra are also good.