Snails come in two main varieties. There are aquatic snails and land snails. If you find yourself asking the question "What do snails eat?" or "what do you feed a pet snail", you first have to find out what kind of snail you have. In general it is easy to know the type of snail because of where you found it. If you found the snail in a marshy area, along a river bank, or pond it might just be better to return the snail if you are not 100% sure of its type.
If you know what kind of snail you have there are two ways to find out what they like to eat.
You can go the trial and error route or you can bring your snail to a local animal store to find out exactly what your snail wants to eat. Being that you are at this site the trial and error approach might suit you better.
Land snails are mainly herbivorous, which means they eat plant life. There are a few snails that are carnivores, but chances are that your snail in not. Snails love to eat just about anything you would put in a garden salad. My recommendation is to start with some romaine, green leaf or even ice burg lettuce. Snails tend to like the softest and wettest part of the plant. If you have an herb garden that produces far more herbs than you need then try picking the newest leaves off of some of your herbs to see if they like them. Apples and carrots can also be a favorite of your pet snail. The key to their diet is to see what grows naturally around the area where you found your snail and bring that to them. During the winter you will have to rely heavily on the produce in your refrigerator to keep them well feed. Remember if the snail is eating all the food you gave him or her then you need to leave more out for them. Slightly rotten food is just fine. They are not terribly picky as long as you give them a food they enjoy.
One last tip: During the spring and fall when your grass is the greenest make sure to cut a big handful of grass for your snail to eat. Both land and the common garden snail love grass and most leaves.
What do water snails eat?
The common water snail is predominately an herbivore. Water snail mainly feed on the algae that will naturally grow on the inside of your fish tank or fish bowl. If you are putting a new snail in a fish tank then watch out! If you have any vegetation in the tank that you are fond of then do not put your snail in the tank. Larger snails can wipe out all plant life in just a few days.
Snails also eat algae along with the microscopic creatures that naturally live in a healthy ecosystem. In most cases you will have to supplement their diet with fish food. Along with fish food cubed up apples and carrots are a favorite. It will take a day or two for the apple or carrot to sink to the bottom. Once on the bottom and partially decayed your pet snails will thank you for the treat.
Tip: If you have more than one snail they are going to reproduce. To help minimize the number of snails in your aquarium you can simply cut back on the about of food you feed your little guys.