How Many Assassin Snails Should I Get? (Complete Guide!)

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Assassin Snails are some of the most interesting critters to keep in an aquarium. But they have their name for a reason.

As they discover the signs of other snails, like Ramshorns or Trumpets, they quickly follow it back to the source. They then climb into the shells of these snails and prevent them from escaping.

So, knowing how many snails you should get will be imperative to maintaining a healthy tank and preventing pest snail infestations.

You can have one or two in a tank as small as five gallons or 10 or more in a tank size of 40 gallons. On average, though, three should be sufficient.

However, your purpose for having Assassin Snails will determine the number you should have. If you want them solely for decorative purposes, then have one or two.

But, if you need to get rid of ample amounts of pest snails, then you will need more that will appropriate the problems you’re experiencing.

Do Assassin Snails Add Bioload?

When we talk about stocking any aquatic organism in the fish tank, the concept of bio-load is also what we should consider.

In very simple words, bioload basically refers to all the waste in the water columns, which is actually the water in your tank.

Now you might be wondering from where does this waste get accumulated in the aquarium?

Well, the answer includes, fish, snails, shrimp, plants, corals, bacteria, as well as microorganisms. In short, anything that is alive, will be contributing to the waste in your aquarium.

And some of the common examples of waste can include, poop, decaying plant matter, uneaten food, fish breathing and any other waste types. So all these wastes are collectively referred to as bioload.

Clear? Good!

Usually nature, the water is moving and the new constantly keeps entering the habitat of the fish. However, in aquariums, once you fill in the water, it’s going to be that only until you do the next water change. No new water will entering in your fish tank.

Due to this fact, a filter becomes helpful in recycling the water, cleaning it before it returns to the fish tank. Now, ideally, filters should clean all the water (100% of it) – and should return it to the state it was present when it first time entered the tank. However, filters are not fully perfect.

Note that when your fish tank bioload increases to a very high level, your filter would fail to keep up with the amount of waste!

So the filter capabilities are what that limit the amount of fish, other live plants and creatures you can have in your aquarium.

Now assassin snails are also a live creature, so you should be considering their biolad as well. But do they add bioload and how much?

Essentially, every living thing generates wastes and assassin snails are no different. The wastes in the water columns is what we refer to as bioload. Assassin snails have a very small bioload.

Although bioload can depend on the snail, but generally speaking, they don’t add too much to the bioload.

Is One Assassin Snail Enough?


One Assassin Snail might be okay, but it really depends on what you plan on having the assassin snail for. Plus, the size of your tank will determine how many will be appropriate. If you want one in a 20 or 30 gallon tank just as a decorative element to the rest of your aquascape, then it will be okay.

But, if you’re trying to get rid of massive infestation of other snails, then you may need more. As a general recommendation, you would need no more than three to start.

What Size Tank Do Assassin Snails Need?

The proper tank size for Assassin Snails is actually quite irrelevant.

They can live in just about any sized aquarium and they don’t influence the water parameters very much. The only caveat here is that they have to have enough food. Having said that, the larger the tank the better it will be for them; especially if you have or plan to have a colony.

This is because a larger tank size provides a nice buffer for managing parameter shifts with nitrites, nitrates and ammonia. So, the number of Assassin Snails you have will depend on your purpose for having them.

How Many Assassin Snails Can Fit in a 5 Gallon?

One to two Assassin Snails will be ideal for a five-gallon tank. But, because this is a very small size, it’s important to be judicious in the amount you have. Only add more than one or two if you have a serious pest snail infestation.

Also, if you plan on breeding the snails, five gallons will not be nearly enough space.

What’s the Best Number of Assassin Snails for a 10 Gallon Tank?

About two to three Assassin Snails should do well in a 10-gallon tank to start. But this is if you’re trying to get rid of an infestation of Trumpet or Ramshorn snails. If your tank is overrun with pest snails and you want quicker results, then you can probably add more.

A 10-gallon aquarium is the general ideal size for housing two Assassin Snails, especially if you want them to spawn. But, if you’re intent on breeding them, then a bigger tank size will be essential.

How Many Assassin Snails Are Good for a 40 Gallon Tank?

You can have as many as 10 Assassin Snails in a 40-gallon tank. But, you have to ensure they will have enough food. Of course, you can have more than that for pest snails. If at some point you find the Assassin Snails finish doing the job you intended, you will have to move them.

This is because they will exterminate all snails and other aquatic life smaller than them in an effort to survive. Remember, assassin snails are carnivores. Once they don’t have enough of their preferred food source, they will probably turn to the next best available food source.

Once your assassin snails consume all the pest snails, you should feed them with a high protein. If you feel, once their pest snail removal task is completed, you can also move them to separate tank and rear them accordingly with their preferred foods.

Apart from eating the pest snails, the assassin snails may also be interested in soft snails eggs, shrimp fry, fish flakes, blood worms and other protein rich supplements.

If you only have a handful of Assassin Snails in a 40-gallon tank, then they should thrive well without exterminating other snails and their young.

Read: Assassin Snails: What And How Do They Kill? (A Complete Guide!)

Should Assassin Snails Stay in a Group?

It isn’t necessary for Assassin Snails to be in a group but they can coexist with about six others at one time. While they don’t mind others of their own kind, it’s going to be up to your own preferences. Unless of course you want to try and breed them, then you’ll definitely have to make sure there are more than three in the tank.

Understand that Assassin Snails tend keep to themselves and don’t often interact with each other while doing their own thing and hunting for something tasty to eat. It’s only when it comes time for them to breed that they begin to intermingle. 

Will Assassin Snails Overpopulate?

Although assassin snails do breed, they breed very slowly for a snail. So they rarely become a pest on their own. Assassin snails lay one egg at a time and it takes about two months for the eggs to hatch.

Once the eggs hatch, the juvenile assassin snails tend to burrow themselves into the substrate. There will be very less chances of seeing them again until they reach the maturity stage.

In general, they reach the maturity stage after about six months, and at that time, they tend to come out of the substrate more regularly.

Read: Do Assassin Snails Eat Algae? (+Top 3 Must-Know Things!)

Final Thoughts

Keeping Assassin Snails in your tank is pretty simple and straightforward. They’re incredibly helpful too, ridding your aquascape of undesirable elements like pest snails. Since they don’t reproduce rapidly, they won’t overtake the tank.

However, if you have too many of them, they can become something of a problem if you’re not careful. That’s it!

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