When buying live plants from pet stores, it is possible to get snail eggs as a bonus. Other kinds of snails can be purchased from the pet store and intentionally added to your aquatic community. There are two main snail types common to freshwater aquariums. Consider the pros and cons of each snail carefully before introducing them to an established aquatic community.
Pros and Cons
Adding snails to your freshwater tanks can have several benefits. In a large tank, they can clean up dead fish and food left from overfeeding as well as remove unwanted algae from tank walls, decorations, and rocks.
If you intend to breed fish, however, snails will diminish your breeding capacity by consuming the fish eggs. Certain kinds of snails will reproduce in mass, so you can easily go from an intended community to an infestation rather rapidly. Also, snails require a higher oxygen density and so require more efficient aerators than the average fish.
Apple snails are usually yellow to brown or black in colour, often with interesting patterns on the shell. They are large aquarium snails that will grow to fit the space they are provided. In a large enough aquarium, their shell, which can reach several inches in diameter, has a potential to grow as large as a baseball before reaching final maturity. In order to reproduce, these snails must be placed into an aquarium as a breeding pair and must be able to leave the water. If the snail does lay a cocoon, look for it in the area of aquarium glass above the water line. These snails are large and will try to go through rather than around objects, so they may damage plants that are not well rooted. Most apple snails are herbivorous, so they will not pose a threat to breeding fish populations and will provide excellent algae control.
Ramshorn snails are, in contrast, very small snails. They average a total length of about 1 centimetre but can grow slightly larger if they survive to full maturity. They have brown or grey shells in a variety of spiral shapes, but they generally look like a spiralled animal horn for which they are named. These snails are asexual, which means that when they reach reproductive maturity they do not need a partner to lay fully fertilised eggs. If you introduce these snails to a tank in which there are no natural predators to control population growth, you can quickly end up with an infestation. Since they lay eggs on plant leaves and on aquarium decorations, it is possible to accidently end up with a hatching in your tank after purchasing these items. They are scavangers that will damage fish egg populations and some plants if they are not getting an ample food source from other means.