Fresh Water Snails: Types, ID, Tank Use and Health Risks

Freshwater snails are gastropods that live in lakes, ponds, rivers and aquariums; Wikipedia counts about 4,000 species. They fall into two broad groups that are easy to tell apart:

• Gilled (operculate) snails breathe with a gill and close the shell with a hard trapdoor, the operculum. Families include the apple and mystery snails (Ampullariidae, 105 to 170 species), the mystery or trapdoor snails (Viviparidae, 125 to 150), and the thiarids such as the Malaysian trumpet snail (about 110) (Wikipedia).
• Pulmonates breathe air with a simple lung and have no trapdoor. Families include the ramshorn snails (Planorbidae, about 250 species), the bladder snails (Physidae, about 80) and the pond snails (Lymnaeidae, about 100) (Wikipedia).

Work through these checks in order. Photograph the shell with the tip pointing up and the opening facing the camera, plus a shot of the snail moving so the head and trapdoor show.

• Does it have a trapdoor (operculum)? Yes means a gilled snail (mystery, apple, nerite, trapdoor or trumpet snail). No means a pulmonate (ramshorn, bladder or pond snail) (Wikipedia).
• Flat, coiled like a rope in one plane? A ramshorn snail (Planorbidae) (Wikipedia; Aquatic Arts sells Planorbarius corneus as ramshorn).
• Small, thin shell under about 16 mm with the opening on the left? A left-coiling (sinistral) shell is the mark of the bladder snail, Physella acuta (Wikipedia). With the tip up and the opening facing you, a sinistral shell opens on the left.
• Tall, pointed cone, burrows in the gravel, most active at night, reddish flecks on a greenish-brown shell? The Malaysian trumpet snail or red-rimmed melania, Melanoides tuberculata (Wikipedia).
• Large round shell, a breathing tube, and egg clutches laid above the waterline? A mystery snail, Pomacea bridgesii (Wikipedia).
• Very large shell, up to 150 mm (6 in), and bright pink or orange egg masses? Possibly the channeled apple snail, Pomacea canaliculata, an invasive species; report it to your state wildlife agency rather than moving it (Wikipedia).

Egg clutches are a strong clue on their own: clutches laid above the waterline point to mystery or apple snails (Wikipedia).

They can be, if you choose the species and control the numbers. What the sources say:

• Clean-up: a controlled population of bladder snails helps clean up leftover food and control algae (Wikipedia). Retailers such as Aquatic Arts sell snails as an algae clean-up crew, and both Aquatic Arts and Shrimpy Business list their snails as peaceful.
• Population booms: bladder snails usually arrive by accident on plants or decorations, can self-fertilise, and adults lay 50 to 100 eggs a week (Wikipedia). Malaysian trumpet snails reproduce without males and carry 1 to 64 young in a brood pouch (Wikipedia).
• Mystery snails need a male and a female to breed, lay eggs above the waterline that hatch in 2 to 4 weeks, can produce up to 200 young from one laying, and cannot survive below 50°F (10°C) (Wikipedia).
• Assassin snails (Clea helena) are sold to eat other snails (Aquatic Arts).

Snails that eat plants can be a problem in planted tanks: the channeled apple snail damages rice and taro crops once it is larger than about 15 mm (Wikipedia).

Prices seen on retailer pages on 25 September 2026:

• Aquatic Arts: B-grade nerite snails from $1.99; assassin snails from $2.99; assorted ramshorn snails from $2.99 (regular $3.99); blue mystery snails from $4.99; Japanese trapdoor snails from $6.99; red racer nerite snails from $7.99.
• Shrimpy Business (sale prices): batik nerite $3.00; horned, zebra, tiger and red pumpkin nerites $6.00 each; red racer nerite $5.00; blueberry snail $14.95.

Sale prices change quickly, and live-arrival terms differ between shops.

Snails do not bite. The risk comes from parasites that use snails as a host and then leave the snail as larvae in the water, or from eating snails raw. The main ones, as described by CDC and Wikipedia:

• Schistosomiasis: larvae released by infected snails get through the skin of people who touch unsafe freshwater (CDC). It occurs in Africa, Asia, the Middle East and parts of the Americas; the schistosomes found in the United States do not infect people (CDC). CDC puts infections at more than 200 million people worldwide, and Wikipedia estimates 10,000 to 200,000 deaths a year. The main snail hosts are Biomphalaria and Bulinus (Wikipedia).
• Swimmer's itch (cercarial dermatitis): an itchy rash from bird and mammal parasites whose larvae come out of snails, in fresh and salt water, including US lakes. It can appear within 12 hours, is not contagious, and usually needs no medical care (CDC).
• Rat lungworm: caught by eating raw or undercooked snails or slugs, or raw produce contaminated by them. Most people recover without treatment, but severe cases cause a form of meningitis (CDC). About 1% of apple snails sold in some Chinese markets carried the parasite (Wikipedia).
• Flukes: the Malaysian trumpet snail hosts 37 trematode species, 11 of which can affect people, including the Chinese liver fluke (Wikipedia).

If you develop a rash, fever, cough or headache after freshwater contact abroad, or after eating snails, see a doctor and mention the exposure.

Handle them with care rather than assuming they are harmless. CDC's advice for snails and slugs: wear gloves when handling them and wash your hands well afterwards, never eat them raw or undercooked, and wash fresh produce thoroughly. For aquarium work, the same habits apply: gloves or a net, and hand-washing after tank maintenance. In places where schistosomiasis occurs, the risk comes from the water itself, so CDC advises avoiding contact with freshwater there.

Aquarium snails that escape can do real damage. The channeled apple snail is on the list of the world's 100 worst invasive alien species and is the worst gastropod invader in Europe (Wikipedia). The bladder snail is now found on every continent except Antarctica and often outcompetes native snails (Wikipedia). The Malaysian trumpet snail has been established in the United States since the 1930s through the aquarium trade and reached 10,000 per square metre in Florida's St. Johns River (Wikipedia). Mystery snails reached the US mainly through the aquarium trade (Wikipedia). Give unwanted snails to another hobbyist or a shop instead of putting them in a pond or stream.

Research and drafting for this page were assisted by AI and checked line by line against the sources listed below. Every number names the organisation it comes from, and where sources disagree we say so instead of picking one silently. Prices and rules are given with the date we checked them (25 September 2026); they change, so confirm before you rely on them. If you find an error, tell us and we will correct it.