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Japanese Trapdoor Snail: Natural Pond & Tank Algae Destroyers

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By Lindsey Stanton

Aquatic Arts 10 Juvenile Japanese Trapdoor Snails

Meet the Japanese Trapdoor snail, also know as JTS, with the scientific name Viviparus malleattus.  People sometimes call them “vivs” for short.  Some folks also refer to them as the Chinese mystery snail.

As far as colors go, you can find these guys in a few varieties:

  • Black
  • Light or dark brown
  • Brown and white
  • White
  • Aqua, white and brown
  • Brilliant aqua

The rarest color is mostly or completely brilliant aqua. The brown tones can vary from a gold/chestnut hue to a redder brown. When these snails are farmed outdoors in large ponds, sometimes algae coats their shell so that they look dark green and fuzzy, but a toothbrush can be used to help remove algae on the shells.

However, their mixed color patterns are often unique to just that snail.


These snails are extremely cold tolerant. Tolerance to very cold temperatures are a major advantage of these snails in outdoor ponds where winters can be intense. Some predators like raccoons will eat them when they are kept outdoors unprotected.

Quick Facts

  • Lifespan: 2-3 Years
  • Temperature: 60-80F
  • pH: 6.5-8
  • Temperament: Peaceful, shy
  • Size: 1-2″

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Where to Buy?

I bought my Japanese Trapdoors online here. None of them died in transit, and they acclimated very quickly. Each one is so different and unique, but beautiful! I recommend buying them online (like me) if you can’t get them locally.


Similar to Malaysian Trumpet snails, Japanese Trapdoor snails are livebearers. They don’t lay eggs. Eggs can be unsightly and annoying to remove, +1 to the JTS, -1 to the Nerite snail… sorry Nerites.

They are also either male or female (non-hermaphroditic), not both at the same time.

Get this: females then have a 9 month gestation period. So you have to wait 9 months after they mate for her to give birth! Unlike Malaysian Trumpet snails, this slow breeding process really helps curb an overpopulation problem like with some “pest” snail varieties. When the female gives birth she lays about 6-20 eggs in one go. She carefully removes the membrane to release the baby.

Sexing can be done by looking at the shape of the snail’s antennae – the female’s tentacles point forward and are even while the male’s right tentacle is larger, shorter, thicker and points to the right as it is slightly curled under (source). It doubles as a reproductive organ.

Tank-born babies are usually born brown or whitish and remain brown for the rest of their lives. They are super cute and grow relatively slowly, especially in cooler temperatures.

The bottom line? Overpopulation is not really an issue with these guys.

Fun fact: Babies often pop up after snails have been shipped, so keep an eye out after getting your new snails for youngsters in your fish tank! They may be eaten by bigger fish if you do not separate them.


What is the difference between the JTS and the Mystery Snail? There are many distinctions, but the main one is easy to spot right away: The shell shape. It has 6-7 whorls with a taller, longer spire shaped like an ice cream cone.

Mystery snails have a more rounded shell shape and fewer whorls (3-4) which are smaller and more compressed together.

Snail expert Matt Reinbold gives us the breakdown:

“Japanese trapdoor” is a name used in the aquarium hobby only, for what are likely Japanese mystery snails (Cipangopaludina japonica). They’re often labeled in the hobby as Viviparus malleatus, but that’s not a real species and takes elements of different genera and subspecies from other taxon within the same family (Viviparidae). By that I mean Viviparus is a valid genus within the family, but not the right genus for these snails. Malleatus is a subspecies or species epithet to a different species in the Cipangopaludina genus. It has nothing to do with your snails or with the Viviparus genus either. Chinese mystery snails are Cipangopaludina chinensis, and are physically very similar to Japanese mystery snails. But they are typically larger, with more bulbous shoulders and the shell isn’t quite as pointed. They’re also not widely found in the aquarium hobby, but are sometimes sold as wild caught snails. Captive born Japanese mystery snails are typically a little smaller than their wild counterparts. The periostracum (the outer protective colored protein layer on the shell) is thinner and stripped away in many areas. Microalgae grows in the exposed calcium, giving it a seafoam green color.”

I’ll admit it: I just had to get these for a few reasons, the main one being I’m a softy for snails. But I wanted to see if these guys could tackle the remaining algae in my 29 gallon that the nerites and the mystery snails had mostly removed. I’d say they have done a pretty good job in the last few months of keeping the green algae at bay. I no longer have to regularly clean the front of the glass, which is a nice plus.


These snails are very slow moving snails. They are also slow-growing snails. They are slow to reproduce and slow in just about every way. But that does not make them any less interesting to watch – they are a fascinating species. They seem to take a while to get off their back if you don’t place them with the opening of the shell facing down.


JTS are pretty flexible when it comes to diet. They love eating algae and decaying matter at the bottom of the pond or tank. Like most snails, they also appreciate food that contains calcium for stronger shell growth (Snello is a great choice for that).

Soft leafy greens and cucumber are also a favorite! Contrary to popular belief, they are very gentle with aquarium plants, unless the plants are dying or the snails or starving. So they do great in planted tanks as well.

Quick fact: The ability of snails to eat mulm and fish waste promotes better plant growth and a more efficient nitrogen cycle!

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Japanese Trapdoor snails make great companions for larger fish like goldfish, thanks to their bigger size. They also do great with almost any freshwater aquarium fish. And they’re also useful to have around. Not to mention super interesting to watch. What’s not to love?

Now I’m turning it over to you. Have you ever owned JTS’s, or are you thinking about getting some for your pond or aquarium?

Leave me a comment below!

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