There was a time when snails were thought to be necessary to have in a home aquarium. The idea was that the snail would clean up the fish droppings and the snail droppings were good for the plants. The plants in turn would give off oxygen that would help keep the fish healthy.
The reality is that the snails don’t eat the fish dropping, and the snail droppings add to the tank debris. Plants can utilize some of the droppings but the rest must be cleaned up by the filtration system. Plants do give off oxygen during the day, but the fish are not dependent upon that oxygen source if you have a good filter that is aerating the water.
The filtration system in the aquarium cleans up the animal matter and provides the necessary aeration to the fish tank. So what do snails do? They clean up excess fish food that would otherwise foul a tank. They help by eating some of the algae that adhere to the tank walls. They eat on the eggs of the fish, breaking them up but not consuming all of the egg before they move on to the next. Snails will also eat on the plants. Most of them usually do not eat the whole plant. They make holes in the plant, weakening them and disturbing the ambiance of the aquarium décor.
There are hundreds of snail species. The most common snails which are most likely to find their way into the aquarium as a stowaway on plants and live food is the Pond Snail. Most of them are prolific breeders. It is necessary to thin the snail population from time to time or they will consume the tank plants. The easiest way to thin the population is to crush them. Many fishes will eat the crushed snails and benefit from the live food.
Some fish breeders raise snails as a source of fish food. Not only will larger fish eat crushed snails, but the snails will help produce infusoria, a collection of tiny single-celled and multi-celled organisms that very small fish can eat. The Apple snails are a common group used to help start infusoria. The snails eat large quantities of plant material, such as lettuce. They produce a large amount digested waste that is a wonderful source of food for infusoria*.
*The use of infusoria was mentioned in an earlier posting.
Breeding fish in a home aquarium
Experiences in setting up a home aquarium
Essential advice for starting a home aquarium
Aquarium gravel and water
Aquarium stands, options and considerations
There are many other fun interesting facts here at Boneblogger.