What Size Should A Neon Tetra Tank Be? (Why It Matters)

Last Updated on 2023-05-24

Contrary to popular belief, caring for fish isn’t too easy. This includes, obviously, the beautiful, colorful neon tetra fish, one of the most popular species of aquarium fish. They need properly treated water that is the right temperature, a great environment to swim in, good tank mates, and other specific conditions as well. However, among the most important is the size of their tank!

You might think that the fish can just be plopped into a goldfish bowl to swim around. After all, what does the size matter? Well, if you think that, you couldn’t be more be wrong! How would you feel if your house was the size of a closet? So, what size tank should you use for neon tetras? Keep reading to find out!

What Size Tank Is Ideal For Neon Tetras?

The ideally sized tank for neon tetras isn’t just about how much one fish can swim around in it. Sure, you can simply plop your fish in a relatively small tank (provided it has the right pH, water temperature, and other water treatment and environmental factors) and keep it alive. However, this isn’t necessarily healthy for the fish and isn’t the tetra’s best living conditions by any stretch.

The minimum tank size for neon tetras is 10 gallons, ideally though, you should keep them in a tank which is 15-20 gallons or bigger. They need to be kept in a school of six, and should be given lots of horizontal swimming space.

To properly care for a neon tetra, a few factors come into play. Although neon tetras are small (only growing to about 1.2 inches in adulthood), they are a shoaling species. This means a few things.

Firstly, it means they need a good amount of other neon tetras in the tank with them! They love to swim in a larger group, so having a good number of fish in your tank is important. Obviously, this means you probably need a bigger tank.

Second, shoaling species need a lot of space to move around in, so a bigger tank is preferred for that reason as well. This is because shoaling species, such as neon tetras tend to move around a lot on multiple levels of the tank.

So, the short answer for “how big should your neon tetra tank be?” is it depends. It depends on how many neon tetras you have if there are other fish in the tank, and of course, your budget.

What Can Happen If You Put Neon Tetras In A Tank Which Is Too Small For Them?

Physical Health

Keeping your neon tetras, or any fish for that matter, in a tank that is too small for them is not only an issue of space and freedom for the fish. It can actually be harmful to your neon tetras’ physical wellness and development as well.

Fish that are put into tanks that are too small for them often grow with deformities or abnormalities. This can include stunted growth, atrophied muscles, and spinal deformities. Generally, this will shorten your neon tetras lifespan significantly!

Social Problems

Not only is the physical health of your fish at risk, but too small a tank can cause problems within the tank between fish as well. This is especially true if there are multiple species of fish in your tank.

Think about it, the smaller the space, the more these fish will come into contact with each other. This leaves plenty of opportunity for aggression, territorial fighting, and other forms of violence you want to avoid.

You’ll want to get a tank big enough for fish to have their own hiding places and cover to swim to when things get heated.

Water Quality

Too small of a tank can also affect the quality of your water. Remember, when your fish eat, that food has to go somewhere! I know, yuck, but it’s important! Too much fish making waste in your aquarium too quickly can seriously impact the quality and conditions of the water, and therefore be harmful to your fish.

Water quality is one of, if not the most important thing for the health of your fish. This includes how polluted the water is, keeping a proper pH and temperature, and making sure these things don’t change due to pollutants contaminating the water.

In a small tank, water quality can go down rather quickly.

Why Are Bigger Tanks Better Than Smaller Tanks?

There are plenty of reasons that a bigger tank is preferred over a smaller tank. It’s not just as simple as them being nicer looking or easier to clean and take care of (although that is a factor). Read on to find out why bigger tanks are so much better than smaller tanks!

Mitigating Problems

Bigger tanks are better than smaller tanks because they help to mitigate or fully avoid all the problems we just mentioned above!

Think about it. In a bigger tank, your neon tetras will have room to grow in a normal way and be fully healthy and happy. Not only that, but they will be able to shoal with their fellow neon tetras while not threatening or being threatened by any other fish you might have in your aquarium.

A bigger tank has more room for fish to swim, shoal, find cover, and hide. All of these important activities can still be done in a smaller tank but with significantly less fish. As we talked about, neon tetras like to swim in larger groups, so a smaller tank is sub-optimal.

A bigger tank is easier to manage water quality-wise as well since the water will reduce in quality a lot slower than in a smaller tank with the same amount of fish.

Simply put, a bigger tank leads to less shredded fins, less dirty water, and longer lives for your neon tetras! It’s worth the investment to get a tank that is properly sized for the proper amount of fish.

Better Viewing

You didn’t buy your fish so they could just live in there, right? Of course not! You want to get a good look at your fish swimming around your tank. Well, a small, cramped tank won’t do them justice, as they won’t be able to swim around in all their colorful glory.

However, a larger tank is perfect for neon tetras. They love to swim horizontally in a group, so a large tank will allow you to really get a great view of their beautiful shoal streaking across the tank!

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Better Landscape

A larger tank has more room for you to give your fish proper cover in the form of plants, driftwood, rocks, or other pieces in your tank, both decorative and functional. This will not only spice up the look of your tank, but it will also allow your fish to behave more naturally, bobbing and weaving in and out of cover and acting more like fish do in nature!

How Many Neon Tetras Can Go In A 10 Gallon Tank?

A 10-gallon tank can hold 6 or 7 neon tetras, no problem! 10 gallons is a fairly small tank, but neon tetras are a fairly small fish, so a few of them should be fine with this sized tank. However, as discussed earlier, this is possibly not the best size tank unless you only have a few fish and you don’t plan on getting any more.

Since neon tetras are a shoaling species, they prefer to be with larger groups of their kind. However, if you’re not planning on picking up any more fish, and you only want 6 or 7 neon tetras, a 10-gallon tank should do just fine.

How Many Neon Tetras Can Go In A 20 Gallon Tank?

A 20-gallon tank can fit up to 24 neon tetras! Now that’s more like it. This higher amount of fish not only makes your neon tetras happy, but their streaking colors swimming quickly across your tank horizontally will look beautiful. 15 is a good minimum number of neon tetras to allow them to shoal properly the way they want to.

A 20-gallon tank is perfect, as not only can it fit a rather large group of neon tetras, it can also create a solid-sized group of neon tetras so they can shoal, as well as leaving some room for a few other kinds of fish!

In a 20 gallon tank, your fish have room to act how they do in nature, allowing you to see your neon tetras in all of their beautiful, natural glory.


So, ideally, the bigger, the better as far as fish tanks go. Even for small fish like neon tetras, a bigger tank will give them more space to grow and flourish and live as they would in nature. This isn’t only important for the health of your neon tetras but also for the viewing experience.

After all, you don’t want to watch boring fish that don’t swim around. You want to watch vibrant colors quickly darting around your tank and large shoals of fish gathering, swimming and swirling around the water.

Ideally, 20 or more gallons is a perfect size. You can work with 10 gallons, but you will need a smaller amount of fish. If you get an even larger tank, such as 30 gallons or more, you can even add other kinds of fish. Just make sure they don’t eat neon tetras!

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