There are some snails that are actually quite beneficial to freshwater aquariums.
The eggs look like blobs of jelly and either float on top of the water or attach to the side of an aquarium when there is at least 2 inches of airspace at the top of the tank. The eggs, or clutches, hatch between two and five weeks after the snail lays them. Sometimes, the snail produces a clutch that is infertile and does not produce babies. Therefore, if the clutch has not hatched within five weeks it may be infertile and you should discard it.
Several varieties of freshwater snails -- including apple, ramshorn, trumpet and pond snails -- are commonly found in fish tanks and aquariums. Each type is unique and often has a specific shell shape. Freshwater snails often breed when in captivity and may produce several babies at a time.
Freshwater Aquarium Snails | The Aquarium Guide
Freshwater Aquarium Snails: Pests or Pets? | Home Aquaria
Aquatic snails are a great addition to any aquarium. They are generally easy to care for and are very interesting to watch. Their water parameters are not very strict and they can handle minor changes. They tend to be hardy, and do not add a lot of biological load to your aquarium. They add another level of aquatic life to the ecosystem of your tank: invertebrates. Freshwater Nerites (pictured above) are among the most popular aquarium snails because of their exceptional algae eating abilities. Although they won’t do all the work for you, they definitely help. Supplement their diet with algae wafers, though, especially when algae are running low. To create an effective algae cleanup crew, get at least around 5 of these snails – they don’t reproduce in the aquarium, so don’t worry about them becoming pests. Be sure to close all holes in the lid, because some Nerites are true escape artists that will try to get out of the aquarium when water conditions are not ideal.Neritidae snails, FW, sel. 7/13/10 Hi, I have been looking for freshwater Neritidae snails. Can you pleasetell me if you handle them or where to get them? Also, in theinformation that I have been able to find about them, some say thatthey will not multiply and others that they will. Which is right? Thanks Rod
Consequently these snails aren't easy to breed in captivity. Thereare a very few exceptions, like the European species Theodoxusfluviatilis, that can complete their life cycle in freshwater. But theones you see in pet shops, such as the African zebra Nerite Neritinanatalensis and the Indo-Pacific zebra Nerite Vittina coromandelianawill not breed under aquarium conditions. Cheers,Neale.> The best way to not let snail populations get out of control is to not get unwanted snails in the first place. This means inspecting live plants before adding them to the aquarium. You can also put the plants in a bucket, with water, and treat the water with a copper-based fertilizer. Copper is toxic to snails so any snails on the plants will die, and then the plants can added to the aquarium. This may seem harsh, but it is important to make sure snails do not overrun a tank.