apple snails are herbivores, so they eat mostly aquatic vegetation, and algae. in captivity, they are commonly fed fish food, along with supplements of rotting organic waste, such as vegetables.. to digest food, apple snails first break up food with the radula teeth, and then the food will be swallowed, and travel down the esophagus and to the stomach. it will eventually exit through the anus as feces. apple snails will eat most aquatic vegetation, and can "ruin" the look of an aquarium very quickly, as they are scavengers.