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Photo: MdE, CC BY-SA 3.0 de

Mystery Snail

Pomacea diffusa

Edited by Ivan F. · Reviewed November 8, 2026

EasyFigures from specialist keeper sources

Beginner verdict

A big, colorful snail with long feelers and a breathing tube, and very entertaining to watch. It scavenges leftovers and algae, and unlike larger apple snails it largely leaves healthy plants alone. It needs hard, calcium-rich water for a strong shell, and a lid to stop it escaping.

Care at a glance

Min tank size: 10 US gal
Temperature: 70–80 °F
pH: 7–8
Hardness: No figure published
Swim zone: Bottom
Min group: Single fish
Lifespan: Up to 2 years

Check your local rules on Mystery Snail

Official lists name this animal or its close relatives. Rules differ by place, so check the rules where you live before you buy or keep one.

Spain
Spain's catalogue of invasive alien species lists the whole apple snail family (Ampullariidae), which includes this snail's genus, Pomacea. The listing covers all of Spain, and it brings a general ban on keeping, transporting and selling live animals.
Source: Real Decreto 630/2013, consolidated text (BOE); Real Decreto 630/2013, consolidated text (BOE), article 7
European Union
EU plant health rules name the whole genus Pomacea as a quarantine pest, at every life stage. The same rules say a quarantine pest may not be brought in, moved, kept, bred or released in the EU. They name the genus rather than this one species.
Source: Implementing Regulation (EU) 2024/2013 (Official Journal copy on BOE); Regulation (EU) 2016/2031, article 5 (Official Journal copy on BOE)
United States
A US Fish and Wildlife Service summary quotes the US Department of Agriculture saying this species, Pomacea diffusa (formerly bridgesii), may move between states without a permit. A 2006 federal notice says other Pomacea species were unlikely to get permits. We could not read the department's own current page, so check before moving snails.
Source: Ecological Risk Screening Summary: Giant Applesnail (US Fish and Wildlife Service); Aquatic Snails; Permit Requirements, Federal Register, 5 April 2006
Alabama
Alabama's wildlife rules ban keeping, selling or bringing into the state any apple snail in the genus Pomacea, which includes this snail.
Source: Alabama Administrative Code, rule 220-2-.26
Georgia
Georgia's wild animal rules require a wild animal license for every apple snail in the genus Pomacea, and they say these snails are licensed only for scientific purposes.
Source: Rules of the Georgia Department of Natural Resources, rule 391-4-8-.05 (Secretary of State); Rules of the Georgia Department of Natural Resources, rule 391-4-8-.05 (Secretary of State)
Idaho
Idaho's invasive species rules list apple snails (Pomacea). Nobody may keep, bring in or move a listed invasive species in Idaho without a permit.
Source: IDAPA 02.06.09, Rules Governing Invasive Species and Noxious Weeds; IDAPA 02.06.09, Rules Governing Invasive Species and Noxious Weeds
Nevada
Nevada's wildlife rules ban bringing in, moving or keeping any apple snail in the genus Pomacea.
Source: Nevada Administrative Code, NAC 503.110
North Carolina
North Carolina's rule on possessing certain fishes names every apple snail in the genus Pomacea, and the state's wildlife commission says keeping anything on that list is unlawful. The official copy of the rule is not served over a secure connection, so we link the commission's page.
Source: Nongame possession and collection (North Carolina Wildlife Resources Commission)
Texas
Texas bans every apple snail in the genus Pomacea except Pomacea bridgesii. The mystery snail sold in shops, Pomacea diffusa, was long sold as Pomacea bridgesii, and the list does not name Pomacea diffusa, so it is unclear whether the exception covers it. Ask Texas Parks and Wildlife before you buy one.
Source: Prohibited Exotic Species: Fish, Shellfish and Aquatic Plants (Texas Parks and Wildlife)

Never release aquarium animals or plants into the wild, including into ponds, rivers or drains.

This is general information, not legal advice. We last checked these lists on 4 November 2026, and the US state lists on 8 November 2026. Our US state aquarium rules table shows every state, including the ones whose lists we could not read. We did not check Spanish regional rules, and other countries have their own.

Mystery Snail care mistakes to avoid

Watch it closely around bettas and other nippers, since they may bite at its long feelers.
Add calcium if your water is soft, because its shell thins without it.
Fit a lid and leave a gap at the top, because it lays egg clutches above the water.
Avoid assassin snails, which prey on it.

Mystery Snail tank mates

Neon Tetra
Paracheirodon innesi
Cardinal Tetra
Paracheirodon axelrodi
Black Neon Tetra
Hyphessobrycon herbertaxelrodi
Glowlight Tetra
Hemigrammus erythrozonus
Harlequin Rasbora
Trigonostigma heteromorpha
Lambchop Rasbora
Trigonostigma espei

Common tank-mate questions

Can Bettas Live With Snails?

Compare

Nerite Snail vs Mystery Snail

How to feed

Feed calcium-rich snail food or blanched spinach.
Let it scavenge leftovers and dead plant matter.
Remove uneaten vegetables after a day to protect water quality.

Mystery Snail FAQ

What size tank do Mystery Snails need?

Our sourced minimum is 10 US gallons (38 liters). A bigger, mature tank is always easier to keep stable.

What can live with Mystery Snails?

Good matches on our list include Neon Tetra, Cardinal Tetra and Black Neon Tetra. Avoid German Blue Ram and Pea Puffer.

How long do Mystery Snails live?

Care guides report about up to 2 years. Stable water and a good diet make the biggest difference.

Will mystery snails take over my tank?

Rarely. They lay visible egg clutches above the water, which you can simply remove, so numbers are easy to control.

Where to buy Mystery Snail

We have not found a store that sells Mystery Snail under its scientific name yet. We add stores as we confirm them.

Live animals and plants travel by courier. Check the store's live-arrival guarantee, and only buy once your tank has cycled (see how to cycle a fish tank).

Not allowed without a permit in: Alabama, Georgia, Idaho, Nevada and North Carolina (see the note above)

The rules are unclear in: Texas (see the note above)

Some US states restrict certain species. Check our US state aquarium rules table and your state's own rules before you buy.

Complete the tank

The essentials for a small, gently filtered tank.

Shop in:

Tank size for this species
At least 10 US gallons (38 L)
Filter
Air-driven sponge filter
Gentle flow that small fish and long fins can handle, plus a safe home for good bacteria.
- Aquarium Co-Op Coarse Sponge Filter (Small) US
  Check the voltage: this filter runs from an air pump, which plugs in. Mains power is about 120 V in the US and about 230 V in Spain, so choose a pump sold for your own country.
  Maker's page
- Fluval AquaClear 20 Power Filter US
  Check the voltage: this model is listed for the US. Mains power is about 120 V in the US and about 230 V in Spain, so do not assume it suits another country.
  Maker's page
- Tetra Brillant Filter Spain
  Check the voltage: this filter runs from an air pump, which plugs in. Mains power is about 120 V in the US and about 230 V in Spain, so choose a pump sold for your own country.
  Maker's page
- Fluval AquaClear 20 Power Filter Spain
  Check the voltage: this model is listed for Spain. Mains power is about 120 V in the US and about 230 V in Spain, so do not assume it suits another country.
  Maker's page · Sold at Kiwoko · Sold at Tiendanimal
Why we chose these (Best Filter for a 10-Gallon Tank). Nobody here has used or tested them.
Heater
Adjustable heater, about 5 W per gallon: 25 W at 5 gallons, 50 W at 10
Keeps a small tank stable. Adjustable models let you set the temperature your species needs. Size up for a cold room.
- Fluval T50 Fully Electronic Aquarium Heater US
  Check the voltage: this model is listed for the US. Mains power is about 120 V in the US and about 230 V in Spain, so do not assume it suits another country.
  Maker's page
- Aqueon Pro Adjustable Heater 50 W US
  Check the voltage: this model is listed for the US. Mains power is about 120 V in the US and about 230 V in Spain, so do not assume it suits another country.
  Maker's page
- Fluval T50 Fully Electronic Aquarium Heater Spain
  Check the voltage: this model is listed for Spain. Mains power is about 120 V in the US and about 230 V in Spain, so do not assume it suits another country.
  Maker's page · Sold at zooplus.es
- Eheim Thermocontrol e 50 Heater Spain
  Check the voltage: this model is listed for Spain. Mains power is about 120 V in the US and about 230 V in Spain, so do not assume it suits another country.
  Maker's page · Sold at Kiwoko · Sold at Tiendanimal
Why we chose these (Best Heater for a 10-Gallon Aquarium). Nobody here has used or tested them.
Water Conditioner
Dechlorinator such as Seachem Prime
Tap water contains chlorine or chloramine that harms fish.
- Seachem Prime US
  Maker's page · Sold at Bulk Reef Supply
- Fritz Complete Water Conditioner US
  Maker's page
- API Betta Water Conditioner US
  Maker's page
- sera aquatan Spain
  Maker's page · Sold at Kiwoko · Sold at Tiendanimal
- Tetra AquaSafe Spain
  Maker's page · Sold at Kiwoko · Sold at Tiendanimal · Sold at zooplus.es
Why we chose these (Best Water Conditioner for Betta Fish). Nobody here has used or tested them.
Test Kit
Liquid kit such as API Freshwater Master
Tracks ammonia, nitrite, nitrate and pH while the tank cycles.
- API Freshwater Master Test Kit US
  Maker's page · Sold at Bulk Reef Supply
- API General & Carbonate Hardness Test Kit US
  Maker's page · Sold at The Shrimp Farm · Sold at Bulk Reef Supply
- sera aqua-test box (Cl) Spain
  Maker's page
- JBL PROAQUATEST COMBISET Plus NH4 Spain
  Maker's page
Why we chose these (Best Test Kit for a Freshwater Aquarium). Nobody here has used or tested them.

Cycle the tank before adding animals. See our guide on how to cycle a fish tank.