How Many Snails per Gallon? {Top 10 Tips For Snail Keeping}

Are you interested in keeping snails in your tank, but you don’t know how many you can safely fit in there? What happens when you have too many snails? In this article, we’ll find out how many snails you can keep per gallon of tank water.

How Many Snails per Gallon? Snails range in length that we will explain in this article, but the general rule is 1 inch of a snail’s body (including its shell) in 1 gallon of water. Too many snails will create an infestation, added waste and lack of available nutrients for them to survive. 

How Many Snails Can I Keep Per Gallon?

You would definitely enjoy the addition of a few snails in a community tank to clean up detritus and unwanted algae growth. You may also keep a tank with only snails if you wish, but please keep the following general of thumb when stocking snails:

  • 1 inch of snail per gallon of water.

This also includes the shell of a snail. We should list some common snails below for you to get an idea of what to expect depending on the length or each species. This way, you can determine how many of each you can keep in your tank.

Average Sizes Of Popular Freshwater Aquarium Snails:

  • Zebra Nerite Snails:  1.5 inches
  • Tiger Nerite Snails:  1 to 1.5 inches
  • Horned Nerite Snails:  0.6 to 1 inch
  • Mystery Snails: 2.5 to 3 inches
  • Japanese Trapdoor Snails:  2 inches
  • Rabbit Snails:  3 to 5 inches
  • Black Devil Snails:  2 to 3 inches
  • Apple Snails: 5 inches
  • Ramshorn Snails: 1 to 2 inches
  • Pond Snails: 1 to 3 inches

If you only have a 5 gallon tank and wish to keep our favorite types of Nerite snails (incredible algae eaters!), then we suggest keeping no more than 3 of them.

How Do I Set Up A Tank For Snails?

We are delighted that you wish to keep snails in your tank and wish to provide you with some helpful tips to make it possible.

Here are our top 10 suggestions:

  1. Keep the water level in the tank about 0.5 inches below the lid of the aquarium giving snails the room to come up for some air.
  2. Always fit the tank with a lid to prevent them from dropping out.
  3. Keep crayfish, crabs or aggressive tankmates known to crush snails away from community tanks that include snails.
  4. Assassin snails will eat other snails so be warned about keeping them with other snail species.
  5. Rapid temperature fluctuations will stress out snails and lead to diseases or sudden death.
  6. Keep the tank away from direct sunlight to prevent overheating and too many algae blooms.
  7. Do not be concerned if your new snails do not move or do anything for their first 2-3 days of adjusting in your tank.
  8. Perform 25% water changes weekly if you are not filtering the tank water. 10% water changes if you have filtration in place.
  9. Use dechlorinated tap water and reduce any copper from pipes or copper based medications.
  10. Add calcium for their shells to remain healthy with cuttlebone, eggshells or liquid based solutions.
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How Many Snails Should I Have In My 10 Gallon Tank?

If you are not inclined to take an exact measurement of each snail, then keep in mind that you probably shouldn’t exceed more than 2 snails in a 10 gallon tank.

Generally 1 inch of a snail’s body fits into 1 gallon of water, but since they vary in size during their lifespan, most snails would enjoy an additional gallon of room to work their way around your tank.

You also face the risk of your snails running out of detritus or algae to consume if they are overcrowded.

Can You Have Too Many Snails in an Aquarium?

Yes! Before you know it, snails can rapidly multiply and become a terrible nuisance in your tank. A snail infestation can throw off your water chemistry.

We employ snails as a clean up crew in our tank, but they also leave waste behind. Adding or allowing them to multiply will make a bigger mess or contribute to a higher bio-load than your nitrogen cycle and beneficial bacteria can handle.

Snails can show up without you expecting it. Their eggs could have been transported without your knowledge on decorations, plants or in the tank water at your local fish shop when you brought a new fish home.


  1. Remove snail eggs when you see them.
  2. Do not crush live snails in the tank because it will raise ammonia levels like a small bursting bomb.

Do Snails Keep Aquariums Clean?

Snails are scavengers are opportunistic feeders on whatever they can find in your tank that is edible. The most popular items on their menu that you have available are:

  • algae
  • decaying plant matter
  • dead aquatic life
  • leftover food

Snails are not looking to eat fish waste. They help to keep your aquarium clean, but they make a mess with their own bio-load as well. This is why we still need to vacuum the substrate and perform water changes.

How Many Mystery Snails Per Gallon?

Mystery snails could arguably the most popular type of snail to keep in aquariums due to their attractive appearance and quirky behavior. They are generally easy to keep.

A Mystery snail grows on average of 2.5 to 3 inches in length including its shell. You will need at least 5 gallons of tank water to keep 2 Mystery snails, but this is still a bit tight for a snail that likes roaming around.

Consider 2 Mystery snails per 10 gallon tank as your best option, but we have a list below for your reference:

  • 5 gallon tank: 1-2 Mystery Snails
  • 10 gallon tank: 2-4 Mystery Snails
  • 20 gallon tank: 4-8 Mystery Snails
  • 30 gallon tank: 6-12 Mystery Snails
  • 40 gallon tank: 8-16 Mystery Snails


Snails are a welcome addition to a community tank if you can prevent them from taking over and becoming a nuisance.

Pond snails tend to multiply rapidly, but many snail types lay copious amounts of eggs that need to be removed to prevent an infestation.

Keep about 2 snails per 10 gallons of water as a safe estimate or 1 inch of snail per 1 gallon of water to be exact.


Thank you for visiting for another article on Snails that we try to explore and explain in great detail through our research and experience as fellow aquarists in this hobby we hope you enjoy as much as we do. See you next time! 

Brian Arial

Brian Arial has kept fish for leisure and worked with fish stores for most of his life. He enjoys writing and caring for aquariums and ponds.

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