Mollusks
Mollusks comprise the mud crab's primary dietary staple. They eat oysters, clams, barnacles, periwinkles and snails. The crabs will use their powerful claws to crush the shells of their prey before eating the flesh hidden inside. Atlantic mud crabs are much smaller than mangrove crabs and eat mostly juvenile mollusks.
Crustaceans
Mud crabs will eat other crustaceans, including hermit crabs. They will grab a hermit crab's shell with one claw and pry the prey out using the other claw. They will also eat other, smaller mud crabs. They are nocturnal predators.
Detritus
Mud crabs will scavenge when the opportunity presents itself and will eat virtually any meaty product. They will eat dead fish that rests on the bottom of marshes or estuaries. Mud crab bait can be made using discarded chicken meat and mullet meat.
Juveniles
Juvenile mud crabs are too small to eat food most adults can manage like clams or oysters. They instead feed on zooplankton, tiny animals that are found floating about the water and smaller crustaceans. They will also eat small snails or other tiny benthic (bottom-dwelling) mollusks.