Aquariums, Information

How Many Fish In A 10 Gallon Tank (Species, Myths & Tips)

Photo of author

by Jason Matthews



Setting up an aquarium is an exciting experience. However, there are many things to consider when putting together your aquarium, especially regarding how to stock it up.

Most aquarists start with a 10-gallon tank because it’s affordable, not too huge, and easy to carry. Fish tanks of this size are popular because they are ideal for beginners and make a great breeder tank for experienced aquarists. However, since the tank is quite small, there’s a possibility of making mistakes.

To avoid this, you need to be knowledgeable about the needs and temperament of your fish to create a healthy ecosystem and prevent premature death. Before putting it in the tank, you must research and understand how to care for every species. But how many fish can you stock up in a 10-gallon tank?

On average, you can have about 5-10 fish in a 10-gallon tank. However, the numbers vary depending on the size of the fish and how much water they generate. If the fish species you have chosen grow fast over time, you should limit the number to 6 or 8.

This article will examine how many fish you can stock up in a 10-gallon tank, what factors to consider, the popular myths, and the types of fish species to choose for your tank.

Key Takeaways

  • Before adding any fish to a 10-gallon tank, consider their behaviors, actual tank volume, and characteristics.
  • The rule of thumb, “one inch of fish per gallon of water,” does not apply in all cases.
  • Some fish species are better suited to survive in a 10-gallon aquarium than others.
how many fish can you have in a 10 gallon tank
[Image by visa vietnam from Pixabay]

What Is The Common Rule Of Thumb?

Most aquarists and pet store staff advise that your aquarium should carry one inch of fish for each gallon of water. While this is good advice, it’s not that simple and could harm your fish. According to PetMD, this is not a great rule because some fish species require more space.

Here are some of the reasons why you should not follow this rule.

The Actual Volume of Your Tank

One of the things that most people don’t consider is that a 10-gallon aquarium does not actually hold 10 gallons of water. The tank usually has additional room for substrates, decorations and ornaments, hardware like filters and heaters, rocks, and driftwood.

Therefore, your 10-gallon aquarium might have about 8 to 9 gallons of water due to the additional materials and evaporation. Therefore, if you follow this rule of thumb, you’ll have to reduce the number of fish species.

Fish Characteristics

The rule also ignores the fish behaviors considering that some species are very territorial. You need to know how different fish species interact before putting them together in a 10-gallon tank.

For instance, if you get Neon Tetras or other schooling fish, they need to be about six; otherwise, they feel threatened and stressed if alone. On the other hand, aggressive territorial fish like male bettas are better suited in their own aquariums without other species.

Furthermore, small tanks like 10 gallons are less stable than the natural habitat of fish species. The best fish to stock in these tanks are hardy species that can easily survive fluctuations in water conditions and parameters. 

You also need to consider the size of the fish species before adding it to the tank. Research the adult size of each species to ensure they don’t outgrow the tank.

What Fish Do Well In A 10-Gallon Tank?

If you just bought a 10-gallon tank, these are some of the options you can consider.


Guppies are a good choice if you are looking for beginner-friendly fish. They are quite easy to care for, and you can breed them without additional assistance. If you add them to a 10-gallon tank, you should have females or males without mixing them.

When adding them to your tank, you can have five to 10 guppies. However, if you are setting up a breeding tank, you should use the ratio of one male to two females and have another tank to transfer your fry.

Neon Tetras

neon tetra for 10 gallon tank
[Image by Leroy Dickson from Pixabay]

The other alternative to consider is the Neon Tetra. As a schooling species, they prefer to be with more of their kind. Neon Tetras are very peaceful and grow to about 1.25 inches long. Therefore, you can fit about 10 of them in a 10-gallon aquarium.

Ensure that you don’t overcrowd them and that the water conditions are pristine. Although they are docile with other fish species, they can nip at each other when they get stressed, which can cause death. This fish species prefer a tank with plenty of plants to hide in, so you can add rocks and driftwood to replicate their natural habitat.


Glofish are schooling fish that come in different species, Glofish Tetras, Glofish Danio, Glofish, Tiger Barbs, and Glowfish Rainbow Sharks. A 10-gallon tank can become overcrowded if you have a lot of decorations with Glofish.

For a tank this size, it’s ideal for a single school of Tetra or Danio species, about 5-6. However, it’s not recommended for Tiger Barbs or Rainbow Sharks because they are slightly aggressive.


pretty goldfish
[Image by Narcis Ciocan from Pixabay]

For a 10-gallon tank, the number of goldfish you can keep depends on the size of the fish. If you want to stock juvenile goldfish or fry, you can keep 3-5 fish in this tank size. However, if you consider keeping adult Goldfish, you can’t keep two of them in a 10-gallon tank. 

Goldfish grow longer; therefore, they’ll need about 20 gallons to swim comfortably.


The minimum recommended tank size for mollies is 10 gallons. However, this tank can only hold 2 mollies. 

These schooling fish are active swimmers; therefore, they need more space than a 10-gallon tank. If you want to add more mollies, you’ll need to upgrade to a 20-30 gallon tank.

Is A 10-Gallon Tank Big Enough For Fish?

It depends on the fish species you choose. Each type of fish has different needs, behaviors, and physical characteristics you should consider before buying the tank.

Does A 10-Gallon Tank Need A Heater?

You’ll need a 50 Watt heater for your 10-gallon aquarium to maintain the right temperatures for your fish.

goldfish in 10 gallon tank
[Image by Kerttu from Pixabay]


Stocking your fish in a 10-gallon tank is an excellent place to begin. However, it might not be ideal for all types of fish. Before choosing the fish species, you need to consider the size, behavior, and amount of water in the aquarium. Once you understand the needs of each species, you’ll have fewer problems stocking.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

Jason aquariume

🐠 Get Your Free Ebook: A Beginner's Guide to Aquariums - Sign Up Now!

Learn everything you need to know to keep fish, including setting up your tank, choosing the right fish, and maintaining water quality. As a subscriber, you'll also stay up-to-date on the latest aquarium products, special offers, and discounts.

Your privacy is important to us. You can trust that we will never share or sell your information, and we'll only send you relevant content.

Leave a Comment