Aquariumsnail · freshwater
Japanese Trapdoor Snail: adult size, tank size & tankmates
The Japanese Trapdoor Snail (Cipangopaludina japonica) grows to about 2.6 in (6.5 cm TL). It needs a tank at least about 10 gallons. It doesn't need a group of its own kind, at 68–85°F.
How big it really gets
Drawn to scale against common tank lengths. Green bars meet the minimum tank length from our sources.
Will it fit your tank?
Quick facts
- Adult size
- 2.6 in (6.5 cm TL)
- Minimum tank
- about 10 gallons
- Temperature
- 68–85°F
- pH
- 6.5–7.3
- Hardness
- not stated
- Group size
- 1 (solitary or pair)
- With other fish
- peaceful
- With its own kind
- peaceful
- Swims
- bottom of the tank
- Diet
- omnivore
- Care level
- beginner
- Lifespan
- 8 years
Japanese Trapdoor Snail tankmates
Checked with the same rules as our tank builder: temperature overlap, pH and hardness, predation and mouth size, fin-nipping and temperament. Tank size is left out here; check it in the builder.
Good tankmates
- Neon TetraAdult ~1.4 in · 70–77°F
- Cardinal TetraAdult ~1.7 in · 73–84°F
- Harlequin RasboraAdult ~2.1 in · 70–82°F
- Ember TetraAdult ~0.9 in · 68–82°F
- Chili RasboraAdult ~0.9 in · 68–82°F
- Celestial Pearl DanioAdult ~1 in · 68–79°F
- Cherry BarbAdult ~2.4 in · 68–81°F
- Rummy-nose TetraAdult ~2.4 in · 73–79°F
- Black Neon TetraAdult ~1.7 in · 73–82°F
- Glowlight TetraAdult ~1.9 in · 75–82°F
Use caution
- Nerite SnailJapanese Trapdoor Snail (pH 6.5–7.3) and Nerite Snail (pH 8–8.4) prefer different pH.
- Mystery SnailJapanese Trapdoor Snail (pH 6.5–7.3) and Mystery Snail (pH unknown) prefer different pH.
- Assassin SnailAssassin Snail eats snails (that's its job as pest control), including Japanese Trapdoor Snail.
- Cockatoo Dwarf CichlidJapanese Trapdoor Snail (pH 6.5–7.3) and Cockatoo Dwarf Cichlid (pH 5–6) prefer different pH.
Avoid
- Blood Parrot CichlidOutgrows tanksBlood Parrot Cichlid eats snails, including Japanese Trapdoor Snail.
- Clown LoachOutgrows tanksClown Loach eats snails, including Japanese Trapdoor Snail.
- Common / Comet GoldfishOutgrows tanksCommon / Comet Goldfish eats snails, including Japanese Trapdoor Snail.
- Convict CichlidNeeds careConvict Cichlid eats snails, including Japanese Trapdoor Snail.
- Electric Blue AcaraNeeds careElectric Blue Acara eats snails, including Japanese Trapdoor Snail.
- Electric Yellow LabNeeds careElectric Yellow Lab eats snails, including Japanese Trapdoor Snail.
- Firemouth CichlidFiremouth Cichlid eats snails, including Japanese Trapdoor Snail.
- OscarOutgrows tanksOscar eats snails, including Japanese Trapdoor Snail.
All 105 species we checked against the Japanese Trapdoor Snail
| Species | Verdict | Why |
|---|---|---|
| African Dwarf Frog | Compatible | No conflicts found |
| Amano Shrimp | Compatible | No conflicts found |
| Angelfish | Compatible | No conflicts found |
| Bala Shark | Compatible | No conflicts found |
| Bamboo Shrimp | Compatible | No conflicts found |
| Betta | Compatible | No conflicts found |
| Black Neon Tetra | Compatible | No conflicts found |
| Black Skirt Tetra | Compatible | No conflicts found |
| Bleeding Heart Tetra | Compatible | No conflicts found |
| Boesemani Rainbowfish | Compatible | No conflicts found |
| Bolivian Ram | Compatible | No conflicts found |
| Bristlenose Pleco | Compatible | No conflicts found |
| Bronze Cory | Compatible | No conflicts found |
| Buenos Aires Tetra | Compatible | No conflicts found |
| Bumblebee Goby | Compatible | No conflicts found |
| Cardinal Tetra | Compatible | No conflicts found |
| Celestial Pearl Danio | Compatible | No conflicts found |
| Cherry Barb | Compatible | No conflicts found |
| Cherry Shrimp | Compatible | No conflicts found |
| Chili Rasbora | Compatible | No conflicts found |
| Chinese Algae Eater | Compatible | No conflicts found |
| Clown Killifish | Compatible | No conflicts found |
| Clown Pleco | Compatible | No conflicts found |
| Common Pleco | Compatible | No conflicts found |
| Congo Tetra | Compatible | No conflicts found |
| Crystal Red Shrimp | Compatible | No conflicts found |
| Denison Barb | Compatible | No conflicts found |
| Diamond Tetra | Compatible | No conflicts found |
| Discus | Compatible | No conflicts found |
| Dwarf Gourami | Compatible | No conflicts found |
| Dwarf Neon Rainbowfish | Compatible | No conflicts found |
| Ember Tetra | Compatible | No conflicts found |
| Endler's Livebearer | Compatible | No conflicts found |
| Fancy Goldfish | Compatible | No conflicts found |
| Forktail Blue-eye | Compatible | No conflicts found |
| German Blue Ram | Compatible | No conflicts found |
| Ghost Shrimp | Compatible | No conflicts found |
| Giant Danio | Compatible | No conflicts found |
| Glass Catfish | Compatible | No conflicts found |
| Glowlight Tetra | Compatible | No conflicts found |
| Gold Barb | Compatible | No conflicts found |
| Guppy | Compatible | No conflicts found |
| Harlequin Rasbora | Compatible | No conflicts found |
| Head-and-tail-light Tetra | Compatible | No conflicts found |
| Hillstream Loach | Compatible | No conflicts found |
| Honey Gourami | Compatible | No conflicts found |
| Iridescent Shark | Compatible | No conflicts found |
| Julii Cory | Compatible | No conflicts found |
| Kissing Gourami | Compatible | No conflicts found |
| Kribensis | Compatible | No conflicts found |
| Kuhli Loach | Compatible | No conflicts found |
| Lambchop Rasbora | Compatible | No conflicts found |
| Lemon Tetra | Compatible | No conflicts found |
| Malaysian Trumpet Snail | Compatible | No conflicts found |
| Marbled Hatchetfish | Compatible | No conflicts found |
| Molly | Compatible | No conflicts found |
| Moonlight Gourami | Compatible | No conflicts found |
| Neon Tetra | Compatible | No conflicts found |
| Odessa Barb | Compatible | No conflicts found |
| Otocinclus | Compatible | No conflicts found |
| Panda Cory | Compatible | No conflicts found |
| Paradise Fish | Compatible | No conflicts found |
| Pearl Danio | Compatible | No conflicts found |
| Pearl Gourami | Compatible | No conflicts found |
| Penguin Tetra | Compatible | No conflicts found |
| Peppered Cory | Compatible | No conflicts found |
| Platy | Compatible | No conflicts found |
| Pristella Tetra | Compatible | No conflicts found |
| Pygmy Cory | Compatible | No conflicts found |
| Rainbow Shark | Compatible | No conflicts found |
| Ramshorn Snail | Compatible | No conflicts found |
| Red-Tail Shark | Compatible | No conflicts found |
| Rosy Barb | Compatible | No conflicts found |
| Rummy-nose Tetra | Compatible | No conflicts found |
| Scissortail Rasbora | Compatible | No conflicts found |
| Serpae Tetra | Compatible | No conflicts found |
| Siamese Algae Eater | Compatible | No conflicts found |
| Silver Hatchetfish | Compatible | No conflicts found |
| Silver Tip Tetra | Compatible | No conflicts found |
| Sparkling Gourami | Compatible | No conflicts found |
| Sterbai Cory | Compatible | No conflicts found |
| Swordtail | Compatible | No conflicts found |
| Three-spot Gourami | Compatible | No conflicts found |
| Tiger Barb | Compatible | No conflicts found |
| Tinfoil Barb | Compatible | No conflicts found |
| Variatus Platy | Compatible | No conflicts found |
| White Cloud Mountain Minnow | Compatible | No conflicts found |
| Zebra Danio | Compatible | No conflicts found |
| Assassin Snail | Caution | Assassin Snail eats snails (that's its job as pest control), including Japanese Trapdoor Snail.; Japanese Trapdoor Snail (pH 6.5–7.3) and Assassin Snail (pH 7.5–8) prefer different pH. |
| Cockatoo Dwarf Cichlid | Caution | Japanese Trapdoor Snail (pH 6.5–7.3) and Cockatoo Dwarf Cichlid (pH 5–6) prefer different pH. |
| Mystery Snail | Caution | Japanese Trapdoor Snail (pH 6.5–7.3) and Mystery Snail (pH unknown) prefer different pH. |
| Nerite Snail | Caution | Japanese Trapdoor Snail (pH 6.5–7.3) and Nerite Snail (pH 8–8.4) prefer different pH. |
| Blood Parrot Cichlid | Avoid | Blood Parrot Cichlid eats snails, including Japanese Trapdoor Snail. |
| Clown Loach | Avoid | Clown Loach eats snails, including Japanese Trapdoor Snail. |
| Common / Comet Goldfish | Avoid | Common / Comet Goldfish eats snails, including Japanese Trapdoor Snail. |
| Convict Cichlid | Avoid | Convict Cichlid eats snails, including Japanese Trapdoor Snail. |
| Electric Blue Acara | Avoid | Electric Blue Acara eats snails, including Japanese Trapdoor Snail. |
| Electric Yellow Lab | Avoid | Electric Yellow Lab eats snails, including Japanese Trapdoor Snail.; Japanese Trapdoor Snail (pH 6.5–7.3) and Electric Yellow Lab (pH 7.7–8.6) prefer different pH. |
| Firemouth Cichlid | Avoid | Firemouth Cichlid eats snails, including Japanese Trapdoor Snail. |
| Oscar | Avoid | Oscar eats snails, including Japanese Trapdoor Snail. |
| Pea Puffer | Avoid | Pea Puffer eats snails, including Japanese Trapdoor Snail. |
| Pictus Catfish | Avoid | Pictus Catfish eats snails, including Japanese Trapdoor Snail. |
| Upside-down Catfish | Avoid | Upside-down Catfish eats snails, including Japanese Trapdoor Snail. |
| Weather Loach | Avoid | Weather Loach eats snails, including Japanese Trapdoor Snail. |
| Yoyo Loach | Avoid | Yoyo Loach eats snails, including Japanese Trapdoor Snail. |
Care notes
Needs: Grazer/filter feeder on algae, biofilm, detritus; survives cold water and northern pond winters; invasive in North America, never release into outdoor ponds or waterways
Group: Not social; live-bearing with separate sexes, slow to breed (mature at ~1 year) and does not usually overpopulate
Temperament: peaceful toward other fish, peaceful toward its own kind. Lives in the bottom of the tank.
Common questions
How big does a Japanese Trapdoor Snail get?
About 2.6 inches (6.5 cm TL) as an adult, according to nas.er.usgs.gov.
What size tank does a Japanese Trapdoor Snail need?
At least about 10 gallons. The smallest standard tank that meets that is a 10 gallon.
How many Japanese Trapdoor Snails should be kept together?
It can be kept on its own. Not social; live-bearing with separate sexes, slow to breed (mature at ~1 year) and does not usually overpopulate
What fish can live with a Japanese Trapdoor Snail?
Species that passed every check include Neon Tetra, Cardinal Tetra, Harlequin Rasbora, Ember Tetra, Chili Rasbora, Celestial Pearl Danio.
Gear for a Japanese Trapdoor Snail setup
TankSmallest standard tank that meets its minimum: 10 gallon (20 in long).Find on Amazon →HeaterAbout 50 W for 10 gallons, holding 68–85°F.Find on Amazon →FoodA quality flake or micro-pellet as a staple.Find on Amazon →Test kitCheck ammonia, nitrite and pH. Cycle the tank before adding fish.Find on Amazon →
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Related guides
Sources
Values come from these pages, in our own words. Status: researched from source pages. Last reviewed 2026-10-12.
- nas.er.usgs.gov /queries/FactSheet.aspx?speciesID=1046
- seagrant.psu.edu /wp-content/uploads/2025/07/Mystery-Snails-AIS-factsheet.pdf
- liveaquaria.com /products/japanese-trapdoor-snail
- aquariadise.com /trapdoor-snail/
- aquariumsource.com /japanese-trapdoor-snail
- journals.gmu.edu /jssr/article/view/4210