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Chinese Mystery Snail

Cipangopaludina chinensis (iNaturalist: Margarya chinensis)[3]

The Chinese mystery snail is a large invasive freshwater snail that lives on the soft bottoms of ponds, lakes, ditches and slow streams.[1][2]

Group
Mollusk
Order
Architaenioglossa
Family
Viviparidae
US records
22 states
Sources
3 cited
Updated
2026-10-16
Chinese mystery snail with a large brown spiral shell held in a hand
Chinese mystery snail with a large brown spiral shell held in a hand. Photo: Anne Parsons, public domain (CC0), via iNaturalist
On this page
  1. Identification
  2. Look-alikes
  3. Where it lives
  4. Biology
  5. Damage and signs
  6. Health risk
  7. Control
  8. Related profiles
  9. Common questions
  10. Sources

How to identify it

  • The smooth, coiled shell grows to about 2 1/2 to 3 inches, taller than wide, and olive green to brown or reddish brown; the inside is white to pale blue.[1][2]
  • A hard operculum, or trapdoor, seals the opening, which is on the right when the shell points up; empty shells lack it.[1][2]

Look-alikes

Look-alikeHow to tell them apart
Japanese mystery snailHas a less compressed shell than the Chinese mystery snail.[1]
Banded mystery snailHas dark rings around the shell, which the Chinese mystery snail lacks.[1]

Where it lives

Native to Southeast Asia, Japan and eastern Russia; sold in San Francisco markets in the late 1800s and established on both coasts by 1965, in the Great Lakes, and in at least 11 Missouri counties.[1][2]

US map: public records from 22 states since 1990 (GBIF).

Biology and life cycle

It prefers soft, muddy or sandy bottoms of shallow, quiet water and crawls on mud and aquatic plants.[1][2]

It spreads through aquarium and bait-bucket releases and by hitching rides on boats and fishing gear.[1]

Damage and signs

  • It competes with native snails, disrupts aquatic food webs, can clog water-intake pipes and dies off in large numbers that foul beaches.[1]
  • In its native range it hosts parasites harmful to people and animals that eat it.[1]

Health risk

Do not eat wild-caught snails: in its native range this species carries parasites harmful to people and animals that eat it.[1]

Control

Prevention

There is no known effective control in waterbodies, so never release aquarium animals or water into the wild, and clean boats and gear between waters.[1][2]

Common questions

What is the big snail in my pond?
A large, smooth snail with a trapdoor may be the invasive Chinese mystery snail.[1][2]
Can I get rid of them?
No effective population control is known; preventing spread is the focus.[1]

Sources

  1. University of Illinois Extension, “Chinese Mystery Snail (Invasive Species).” extension.illinois.edu/invasives/chinese-mystery-snail (accessed 2026-10-16)
  2. Missouri Department of Conservation, “Chinese Mysterysnail (Field Guide).” mdc.mo.gov/discover-nature/field-guide/chinese-mysterysnail (accessed 2026-10-16)
  3. iNaturalist, “Margarya chinensis taxon page (order and family).” www.inaturalist.org/taxa/1672221 (accessed 2026-10-06)

Updated 2026-10-16. Built from sourced records. Spot an error? Tell us.