The Complete Guide to Japanese Trapdoor Snail Care

japanese trapdoor snail

Classified in many areas of the world as an invasive species, Japanese Trapdoor Snails should not be discounted as a vital addition to your community aquarium. These mollusks are 2 inches of powerhouse cleaning that will all but rid your tank of algae and detritus from plants and leftover food.

Japanese Trapdoor Snails are low maintenance, easy to care for, and suitable for aspiring hobbyists, and can even be used in an outdoor pond if you’re lucky enough to have one in your yard.

With a 10-gallon tank size minimum, you don’t need a lot of space to keep them, and they won’t get lost in a larger tank, either.

I find Japanese Trapdoor Snails fun to watch–they’re beautiful to look at, and although they are super peaceful creatures, they are anything but boring.

You’ll be excited to see how clean your water gets and how much less often you’ll have to clean the tank glass once you have a few of these in your aquarium. They love plant waste, but won’t destroy your live plants.

Read on to find out everything you need to know about caring for Japanese Trapdoor Snails as well as what they can do to improve conditions in your aquarium. It probably won’t even take you to the end of this article to decide you want to go out and get a few for your tank.

Japanese Trapdoor Snail Facts & Overview

japanese trapdoor snail

Care Level:Easy
Color Form:Black, tan, cream
Lifespan:15-10 years
Size:2 inches
Minimum Tank Size:10 gallons
Tank Set-Up:Freshwater with rocks and wood
Compatibility:Peaceful community

Japanese Trapdoor Snails, scientific name Viviparus malleattus, are originally native to Asia, particularly China, Japan, Myanmar (Burma), and Thailand. However, they can now be found pretty much worldwide. It’s likely that the Japanese Trapdoor Snails are an aquarium hobby name for Japanese Mystery Snails, scientific name Cipangopaludina japonica, and the species are sometimes referred to interchangeably.

Also known as the Chinese Mystery Snail, Japanese Trapdoor Snails are livebearers–in fact, they have an extremely long gestation period of 9 months. Their shells are usually black, grey, or tan, but sometimes you’ll see an aqua one.

In the late 1800s, these snails were introduced to San Francisco via a fish market, where they were sold as food. From there, they made their way into the San Francisco Bay, where they remain today.

Their natural habitats are ponds and streams with slow currents. They are happy as clams in mud, as they can find lots of nutrition in the algae and plant detritus.

Although they are considered an invasive species in some areas of the world, in the aquarium world, they are championed as excellent tank cleaners, as they scavenge the tank for algae and detritus, improving water quality for other aquarium inhabitants.

Fun Fact: Although Japanese Trapdoor Snails love algae and plant detritus, they are completely uninterested in your live plants, so you don’t have to worry about these snails destroying your planted or floating greens.

You might notice that Japanese Trapdoor Snails do not have the protruding tube that many snail species have. This tube, known as the siphon, helps snails breathe air, and is not present in Japanese Trapdoor Snails. That’s because Japanese Trapdoor Snails are completely aquatic and do not breathe air.

That might seem odd, but not having a lung allows them to survive in incredibly cold water, even below freezing. They are hardy creatures. Indeed, Japanese Trapdoor Snails have a longer lifespan than many aquatic snails, living for 5-10 years!

Friend or Foe?

Some states consider Japanese Trapdoor Snails to be an invasive species and will not allow you to keep them as pets or in captivity. You should check the local regulations in your area before purchasing any Japanese Trapdoor Snails.


If you keep an outdoor pond, Japanese Trapdoor Snails serve as great cleaners. They will munch up all your algae, and if you live in a cold climate, they can withstand frigid temperatures.

They will also rid your aquarium, pond, or water garden of dead sections of plants without harming the live sections. More trash for you, food for them includes leftover fish food and detritus.

Peaceful creatures, Japanese Trapdoor Snails are more in danger of being eaten than they are a risk to anyone else.

Typical Behavior

Japanese Trapdoor Snails are peaceful scavengers. You’ll have a great time watching them explore the tank in search of food, and like a great houseguest who always cleans up after themselves and others, Japanese Trapdoor Snails will rid your tank of all things undesirable.

One thing that I can guarantee is that Japanese Trapdoor Snails have zero interest in bothering anybody else in your home aquarium. They won’t hassle other residents and are not phased by other goings-on in the tank.

Their main interest and attention are searching for snacks, which makes them happy and you happy (since you get a clean tank)– a win-win!

Snails have a reputation for being slow and inactive, but these guys are movers and shakers in the tank. They are particularly active at night, so if you’re a night owl, you’ll see them roaming around.

It’s not uncommon for Japanese Trapdoor Snails to hide out in their shells for extended periods–that trapdoor (operculum) is designed to protect them from predators, and sometimes they just need a little time out. If your Japanese Trapdoor Snail is not in hiding and has actually died, you’ll know from the strong odor and increased ammonia in the water.

One other behavioral tic to watch out for is the tendency for Japanese Trapdoor Snails to come up to the water’s surface, so you may want to keep the water level lower so that they don’t get too far up.


One cool thing about Japanese Trapdoor Snails is that each one is a little bit different looking, whether that variation is seen in the spirals or the colors on their shells.

Generally, Japanese Trapdoor Snails have 3 whorls, which taper and thin as they move upwards on the shell. That 3 is not a hard number, however. Sometimes they have more than 4 whorls.

In terms of coloration, Japanese Trapdoor Snails display one color on the first whorl at their base, and then the other whorls have rings of different colors, and the base color often gets lighter as it gets further away from the snail’s body.

Commonly black, cream, and tan, Japanese Trapdoor Snails sometimes sport brighter colors. Another fun feature of these gastropods is that the lines on their whorls are often textured.

You’ll also see their operculum, which protects them from predators and affords them some privacy. Predictably, this is the source of their name, as the operculum acts like a trap door. The snails pull the operculum over their shell’s opening, just like I sometimes pull the blanket over my head when I just can’t deal.

How big are they?

Japanese Trapdoor Snails are on the larger side of the snail spectrum, measuring in at about 2 inches. How big they grow depends on the care you give them, as well as how they were bred.

Distinguishing between males and females

There is not a whole lot that differentiates the females from the males, but the females tend to have long antennae, while the males’ antennae are shorter and lean to the right. Japanese Trapdoor Snails are non-hermaphroditic, so they are either male or female.

Habitat and Tank Conditions

The habitat and tank conditions that you provide for your Japanese Trapdoor Snails will likely be the habitat and tank conditions that their tank mates require. However, there are certain elements, particularly at the tank bottom, that you want to consider for your beautiful gastropods.

The substrate needs to be a softer surface since a rough substrate could easily irritate Japanese Trapdoor Snails, who spend their days dragging themselves along the bottom. Worse than irritation, they could even cut themselves, leading to infection.

I recommend a soft and sandy substrate. If you are hoping to add Japanese Trapdoor Snails to an established tank that has a gravel substrate, you may want to hold off, as changing the substrate can negatively impact the biosphere of the community. Mud, found in their natural habitat, is also a good substrate option.

You also want to make sure that you have lots of plants–the detritus from decaying plant matter is an essential part of their nutrition. Other habitat additions are wood and rocks, which collect the Japanese Trapdoor Snail’s beloved algae.

And although Japanese Trapdoor Snails will do wonders for the water quality in your community aquarium, you will still likely need a filter. I recommend covering the intake so you don’t lose Japanese Trapdoor Snails to the filter.

Water Conditions

Japanese Trapdoor Snails are very forgiving about their water parameters and can survive even in harsh conditions. Of course, you should aim to provide optimal conditions so that they can live a long and joyful life scavenging around your tank.

Because they are usually members of community tanks, and freshwater fish often have more strict water parameters, you’ll want to make sure that you hit the Japanese Trapdoor Snail’s water needs while still honoring the needs of the fish.

I recommend doing water checks often when you first introduce Japanese Trapdoor Snails to your aquarium. As hardy and adaptable as they are, they do need stability. If there is a sudden change, your snails will likely not respond well. So, for example, they can handle both 68°F (20°C) to 88°F (31.1° C), but you would not want to quickly switch from the lower number to the higher number or vice versa.

The optimal parameters to ensure the best quality of life for Japanese Trapdoor Snails:

  • pH levels: 6.5 to 8
  • Water hardness: soft to medium
  • Water temperature: 68° to 88°F (20° to 31.1° C)

What Size Aquarium Do They Need?

You will need at least a 10-gallon tank to accommodate Japanese Trapdoor Snails; they don’t require a lot of space. However, you should remember that if you are keeping multiples, or housing them with other aquatic pets, you’ll need a bigger tank.

Of course, if you are keeping fish, their tank size requirements will take precedence over the Japanese Trapdoor Snails.

How Many Can Be Kept Per Gallon?

You could keep 5 or 6 Rosy Red Minnows in a 10-gallon tank, although if you can go bigger, that would be better.

Tank Mates

Japanese Trapdoor Snails are unassuming and mellow aquarium mates. Your choice for tank mates is more dependent on whether the tank mate wants to eat them for lunch. The Japanese Trapdoor Snails won’t cause trouble for anybody else.

Additionally, because of their flexibility in water temperature and parameters, they will survive with many different types of fish and aquarium species. Note: Keep them away from Assassin Snails.

Appropriate tank mates for Japanese Trapdoor Snails include

Keeping Japanese Trapdoor Snails Together

Japanese Trapdoor Snails can definitely be kept together. In fact, they are often sold in groups of 5, 10, or 20.


While your Japanese Trapdoor Snails will be super happy with the algae and detritus provided by evidence of living things in your tank, you will need to supplement their diet. They’re omnivores that eat greens and protein.

You should offer plant-based pellets and bottom feeder tablets; they will also eat live food and frozen food.

One thing I want to state clearly is that you shouldn’t assume you have carte blanche to overfeed your other fish because the Japanese Trapdoor Snails will eat the leftovers. Not only will too much food negatively impact water quality, but many fish don’t know how to stop eating when they’re full.

You could also supplement their diet with vegetables, such as blanched cucumbers, kale, lettuce, spinach, and zucchini.


Japanese Trapdoor Snails are low-maintenance aquarium residents and will likely decrease the amount of maintenance you’ll have to do to maintain your tank. However, you can’t just ignore them, either.

Follow the water parameters I recommended above; even though they can survive in extreme conditions, you always want to make sure to provide your pets with optimal conditions that will ensure they thrive, not just survive.

One of the best things you can do for your Japanese Trapdoor Snails is making sure they are not living with predatory creatures that will suck them right out of their shells.

Japanese Trapdoor Snails are not afflicted with many diseases, though I do want to note that if you’re treating your aquarium fish for disease, avoid medications with copper, which is toxic to snails. You should also avoid tap water, which has copper.

Older snails are susceptible to Oedema, or fluid build-up in the tissues. As in humans, swelling from fluid build-up can cause severe health issues and even death. Sadly, there is not much you can do to reverse Oedema.

As you do with any of your aquarium friends, you should perform regular water changes (yes, even though Japanese Trapdoor Snails are great cleaners, they are not going to do all the work for you). You should also do regular water testing, and watch your snails for behavioral changes or other signs that they might be sick.


Unlike some snail species that breed so fast you may find them taking over your tank, Japanese Trapdoor Snails have a 9-month gestation period, so you won’t have to worry about overpopulation.

These mollusks reach reproductive maturity at about one year of age. Japanese Trapdoor Snails are livebearers that birth up to 20 snails per cycle. The females use their tentacles to hold the newborn snails and remove the membranes that surround them. (That’s probably why the females have those longer tentacles.)

You don’t need a separate breeding tank, and you don’t need to do anything special to encourage breeding. It will just happen naturally in the aquarium.

Are Japanese Trapdoor Snails Suitable for your Aquarium?

I highly recommend adding some Japanese Trapdoor Snails to your community aquarium. They’re easy to care for, and the benefits of having them around to clean your tank should not be ignored.

I’ve heard from so many aquarists about how the cleanliness of their aquariums increased exponentially after adding a couple of Japanese Trapdoor Snails. Water is no longer murky, and there’s no need to constantly be cleaning algae off the aquarium glass.

If your area doesn’t prevent you from keeping Japanese Trapdoor Snails, they’re a great choice for your tank. If your area does consider them an invasive species, don’t risk getting one. They may seem like innocuous additions, but in the wild, invasive species can alter the natural habitat, disrupt food sources, and endanger other creatures as a result.

But if your area gives you the green light for having these hardy helpers, you won’t be disappointed with these entertaining mollusks.

Do you keep Japanese Trapdoor Snails as pets or do you view them as an invasive species? We’d love to know your experiences with these snails, so please share in the comments below.


Is my Japanese Trapdoor Snail a vegetarian?

Actually, although they love algae and decayed plants, Japanese Trapdoor Snails are omnivores, and you should provide them with sources of protein as well as greens.

Do I need to have a separate breeding tank?

Japanese Trapdoor Snails are low maintenance to breed; they do not require a separate breeding tank nor special conditions. They will just do their thing in the tank, and you can expect to see live births 9 months after fertilization.

What is the average lifespan for Japanese Trapdoor Snails?

Japanese Trapdoor Snails have a long lifespan as far as snails are concerned. Provided with optimal conditions, you can expect these helpful gastropods to live between 5 and 10 years.

Are Japanese Trapdoor Snails helpers or pests?

That depends on who you talk to. In the captive quarters of your home aquarium, they are helpers, cleaning your tank and improving water conditions day after day. However, in the wild, they are often considered invasive species who disrupt the natural habitat and processes, often negatively impacting food sources for other creatures, putting them at risk. Therefore, if you live in an area where Japanese Trapdoor Snails are considered invasive, you will not be able to keep them in captivity, either.

About Robert 468 Articles
Robert Woods is the creator of FishKeeping World, a third-generation fish keeper, and a graduate in animal welfare and behavior. He is also a proud member of the Association of Zoos and Aquariums, the Marine Aquarium Societies of North America, and the Nature Conservancy.

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