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There are many different varieties of aquatic snail, though the most common varieties you'll encounter are the Gold Inca, mystery, nerite, pond, ramshorn, and trumpet snails. Each one is marked by its own distinct features. Which snail you choose may depend on your aesthetic preferences, your tank's needs, or both.  Gold Inca snails are recognizable by their bright, yellow shells. Gold Inca snails are considered good cleaners of freshwater tanks, as they tend to consume algae and detritus. Ivory snails are identified by their cream-colored shells. Ivory snails are also considered good tank cleaners and "scavengers" of freshwater aquariums. Mystery snails have a shell that tends to vary in appearance, but is usually somewhat dark (though some are ivory), typically with brown accents or stripes. Mystery snails have a tendency to scavenge, but they can also easily escape tanks and will most likely require a secure lid. Nerite snails come in different shapes, colors, and patterns, depending on the variety of snail. Nerite snails tend to scavenge for algae, but they also burrow into the substrate at the bottom in search of food. Pond snails are one of the most frequently-encountered unwanted snails. Pond snails tend to travel on aquatic plants and in aquarium water, often inadvertently making their way home from the pet store to a new home. Ramshorn snails have a shell that appears to twist and curl, much like the horn on the head of a ram (hence the name). Ramshorn snails are good scavengers, but like pond snails they often end up in home aquariums by accident. Trumpet snails tend to have elongated and cone-shaped shells. Trumpet snails are excellent scavengers, but like pond snails and ramshorn snails, they often appear without invitation in new aquariums due to their ability to sneak in on freshwater plants. Saltwater snails are also a popular addition to many marine tanks. They tend to eat algae and plant matter just like freshwater snails do, but some snails are carnivorous. They also tend to be more colorful than their freshwater counterparts. For this reason, many aquarium enthusiasts prefer saltwater snails for their home tanks. Which snail you choose will largely depend on your personal aesthetics and your home aquarium setup.  Bumble bee snails are carnivorous invertebrates. They typically eat meat-based detritus, including decomposing organisms in the tank, and have been known to eat other snails in the tank when food is scarce.  Cerith snails are easy to care for and can help improve oxygenation within the substrate of an aquarium. They scavenge for algae, detritus, leftover food, and fish waste.  Nassarius snails eat detritus, leftover food, decaying plant material, and fish wastes. They are excellent at keeping aquariums clean as they typically seek out a lot of food within the tank.  Turbo snails are generally easy to care for and tend to be very colorful. They come in a number of varieties, including Astraea turbo snails and chestnut turbo snails, and they tend to feed on algae and dried seaweed flakes. If you're new to keeping aquatic snails, you may be uncertain about what to look for while selecting a snail. Avoid any snail that exhibits a loss of color, a lack of appetite, an inability to move/exert energy, a tendency to hide inside its shell, or visible spots or other types of fungus anywhere on the body or mouth, as these snails are most likely ill or carrying parasites. When you choose a snail, look for the following signs of good health:  active movement within the water a healthy appetite for whatever type of food that snail prefers consistent/evenly-distributed coloring a clean shell It's important to be aware of the risks that come with certain varieties of aquatic snails. Some varieties are considered "pests," appearing unexpectedly and reproducing on a large scale. These population booms can reduce oxygen content in the water, increase the levels of carbon dioxide, and create a great deal of organic waste through their excrement and eventual decomposition. When choosing aquatic snails, it's best to select snail varieties that are not generally considered pests by aquarium owners.  Ramshorn snails are considered one of the biggest pest varieties. These snails reproduce quickly and in very large numbers. Pond snails and trumpet snails are also considered pests by many aquarium owners, though some owners select these snails for aesthetic reasons. Talk to an aquarium expert at your local pet store if you're not sure whether a particular variety of snail might become a pest in your tank.

Summary:
Identify the different types of freshwater snail. Learn about different varieties of saltwater snails. Choose a healthy-looking snail. Recognize the risks of certain varieties.