Mystery snails should be fed a varied diet of algae or veggie wafers, fish pellets or flakes, and freshly blanched vegetables. The chief component, or "staple", of a Mystery snail's diet should be dried and blanched foods. They need lots of calcium in their diet to properly build their large shells. This can be obtained by feeding lots of blanched vegetables or supplementing with calcium tablets. Good blanched vegetables for Mystery snails include carrots, cabbage, cucumbers, zucchini, and spinach. Iceberg lettuce contains little nutritional value for the snails, so cabbage is usually chosen instead.
Mystery snails will also feed partly on bio-film and algae that grows in the aquarium.
When feeding your snails, it is important to remember that though they eat very slowly, old food must be removed after a few hours. When figuring out how much staple food to feed your snails, just place one algae wafer near the front of the aquarium so that you can see it easily. After a few hours look at how much food is left, and subtract that amount from the next staple feeding.
Mystery snail babies will feed on the same things that adults eat- they, too, need lots of calcium.