What do apple snails eat?

Apple Snail Diet

Mostly they love algae. This is why they move up and down the sides of your tank-they are eating algae. Even if the glass looks clean, there is microscopic algae there. However, if you have a brand-new tank that has no algae at all, you need to purchase algae tablets at the pet store so the snails will not starve before the tank grows it's own algae.
Here is more input:

• Apple snails cannot thrive on algae, and they're not very effective at removing it. They do love apples and other fresh fruit, vegetables, and sinking herbivore wafers. If you visit the discussion forums on applesnail.net you will even find recipies that people have created for apple snail food and treats. :)

• Floating pond fish food called Ten Six. They love it and will take it from your fingers if they are foraging at the top of the tank.

• Shrimp Pellets Formula

• My apple snails eat algae, micro-organisms, and algae wafers. They started to grow quite fast when I fed them the wafers. Their name refers to their potential size, not what you feed them, and they can actually get larger than apples, larger than an outstretched hand, in fact.

• 
  Only certain species of Applesnails will grow palm-size or larger. These are usually Pomacea Canaliculata species. I feed my snails a wide variety of foods including, but not limited to, fresh leafy greens from the grocery store, dried bloodworms, tubiflex worms, live mealworms(though they usually drown and die quickly, the snails still enjoy them), goldfish crumbles, koi pellets, reptile pellets, fresh plants, algae-covered rocks from local clean rivers, tomatoes, bananas, green beans are a favorite, and white bread.
• I have to add that after reading this article my partner put banana and tomatoes in our aquarium to feedour apple snails and within 8 hours my tank was toxic and i had to do a 100% water change! I cannot be certain that this was due to the food i added, but nothing else new entered the tank and the levels were normal before this. Be warned, i wouldn't risk it!