Neon Tetra Tank Size: Everything You Need To Know

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They may be hardy, low-maintenance fish but it’s still important to choose the right Neon Tetra tank size to keep them healthy and happy.

If you choose a tank that’s too small for the number of fish, your Neon Tetras won’t have the swimming room they need to display schooling behaviour, but more importantly you risk your fish suffering from health problems that can even lead to death.

In this article I’ll cover:

  • The minimum number of Neon Tetras that should be kept together in a group
  • How much swimming space is needed
  • How the above impacts the minimum Neon Tetra aquarium size
  • The dimensions the tank should ideally have (wider is better than taller!)
  • Why 30 gallons is the ideal tank size for Neons

Let’s get into it!

Neon Tetra

What is the minimum number of Neon Tetras to keep in a tank?

The minimum number of Neon Tetras that should be kept in any tank is 6, but ideally you should aim for no fewer than 10.

This is because Neons are schooling fish. Schooling is different from shoaling, which just means that they stay together for social reasons.

Schooling fish swim in the same direction and appear to move as one, but the movement is not choreographed. Instead they respond very quickly to stimuli, and the group all learn to respond in the correct way as juveniles.

Schooling fish have a ‘safety in numbers’ mentality – schooling helps avoid predators as it can be hard to isolate a single fish to attack. The larger the school, the safer your Neon Tetras will feel.

Schooling also conserves energy. The less friction in the water, the easier it is to swim. Not to mention that it helps when hunting prey – everyone working together increases the chance of catching a meal.

Can I keep 4 Neon Tetras?

It is of course possible to have fewer than the recommended minimum, but there are severe downsides for you and your fish. It’s against a Neon Tetra’s nature to be alone – a single tetra will develop depression.

Depression weakens the fish’s physical health, and lowers immunity. There is always a very real threat that a lone Neon Tetra will literally die from being kept on their own, regardless of the size of the tank or water quality. Keep them happy and there’s every chance your Neon Tetras will live around 6 years.

Neon Tetra

Do Neon Tetras need lots of space to swim?

Neon Tetras need lots of swimming space, because Neons are schooling fish. Ornaments, plants and rocks take up that swimming space, so be sure to leave plenty of open water for your Neon Tetras to school.

If you’re keeping too many Neons in too small a tank, or filling the swimming space with too much ‘stuff’, your fish will become stressed. Stressed fish are more sensitive to poor water quality, so it’s important to consider this as well.

Even if you have lots of space in the tank compared to the number of fish, it’s important to perform regular water changes to keep the water quality optimal. Even low bioload fish like Neon Tetras poop, so make sure you’re checking your water parameters and keeping up the proper maintenance.

How much tank space do Neon Tetras need?

Assuming you keep the minimum recommended number of six Neons, then ten gallons is the minimum amount of space required for a Neon Tetra tank.

Rather than asking what is the minimum number of Neon Tetras you can keep, it’s better to consider how much space you have in your tank and working from there. If you have less than 10 gallons, Neon Tetras are probably not the fish for you, as this is too small for the bare minimum of 6 Neons in a group.

By the often-used “one inch per gallon” rule you’d be looking at 2/3 of a Neon Tetra per gallon, or one Neon every 1.5 gallons. However with Neon Tetra, minimum tank size is more complicated and this is only a very loose rule of thumb.

There is much more to consider when buying schooling fish, which are happier in larger groups (provided the tank can accommodate). Look for a bigger tank and then increase the size of your group, remembering that Neon Tetras grow to between 1.5 and 2 inches.

  • How many Neon Tetras for a 10 gallon tank?
    • In a 10 gallon tank you can fit no more than 6 Neons, which is the absolute minimum Neon Tetra group size. This assumes your tank isn’t heavily planted and that not too much space is taken up by rocks, ornaments etc.
  • How many Neon Tetras in a 15 gallon tank?
    • A 15-gallon tank should be suitable for around 8-9 Neon Tetras. At this point the shoal is becoming big enough to provide the fish with the feeling of security that encourages strong shoaling behavior.
  • How many Neon Tetras in a 20 gallon tank?
    • In a 20 gallon tank, you should comfortably fit 11-12 Neon tetras as long as there is plenty of swimming space and adequate filtration.
  • How many Neon Tetras for a 30 gallon tank?
    • You can easily stock 15-20 Neon Tetras in a 30 gallon tank as long as it is filtered and well-maintained, with lots of swimming space for the fish to school (or more accurately, shoal).

Number of recommended Neon Tetras by tank size:

GallonsNumber of Neon Tetras
Use this table as a guide, but not a calculation of a hard-and-fast maximum. More experienced fishkeepers who understand tank parameters and undergo regular water changes could push these limits a little, provided that again, there is adequate swimming space.

Neon Tetra tank dimensions

Horizontal space is more important than vertical depth for Neon tetras, as they need room to school together from one side of the tank to the other. You don’t need to go overboard here, a 30 gallon tank that’s 36 inches in length (like this one) is fine.

What is the ideal tank size for Neon Tetras?

The ideal tank size for Neon Tetras is 20-30 gallons. This allows a group of around 15 happy, healthy fish without being over-stocked, which is the number where you should see impressive schooling behaviour.

Again, the more tankmates, plants, rocks and other ornaments are present in the tank, the less actual space is available and the fewer fish will comfortably fit in a tank of any size.

Neon Tetra
“Classic Neon Tetra” by Moto@Club4AG is licensed under CC BY 2.0

Tankmates for Neon Tetras

This should be obvious, but any other fish being kept in the tank will reduce the number of tetras that it’s appropriate to keep. Here’s a couple of factors to consider:

  • The bioload of potential tankmates: higher bioload fish like plecos will reduce water quality by pooping in high quantities, so regular cleaning and water changes will be needed to prevent your Neons from getting sick.
  • The size of potential tankmates: – the bigger the tankmates, the less swimming space for your Neons. You could easily keep Neon Tetras with discus fish, for example, but they grow to around 8 inches – that’s more than 4 times the size of your average Neon, so adjust your numbers accordingly.

What do Neon Tetras like in their tank?

Neon Tetras are a peaceful and timid fish who can easily feel threatened with other species around, so they love decorations like rocks and caves. They especially like to have live plants so they can hide around the roots and leaves when they need to feel safe.

My Neons like to explore the Amazon Sword plants that provide most of the greenery in my community tank. As a bonus, they’re super easy to grow and look after.


The answer to the question ‘what is the minimum tank size for Neon Tetras’ is based on a combination of factors:

  1. Make the health and happiness of your fish the top priority – schooling fish thrive in larger groups
  2. The bigger the group, the bigger the tank needed to ensure they have adequate space
  3. Water quality is affected by having too many fish in too small a tank and should always be monitored regardless of being under or over-stocked. Invest in a good quality testing kit (I use this one!)
  4. Swimming space is just as important than tank capacity – for Neon Tetras, choose horizontal space over vertical to allow for schooling behaviour and don’t over-fill your tank with plants, rocks and ornaments
  5. Tank mates take up space too, so reduce the amount of Neons accordingly (and research which fish are suitable tankmates for Neon Tetras!)

How many Neon Tetras should I get?

Go for a 30 gallon tank and stock with around 15 Neon Tetras. This is a big enough group to start showing some really impressive shoaling behavior. You’ll also have room for decorations, live plants and some tankmates, for example 5-6 guppies and some Amano Shrimps.

You should also have some room for plants and rocks as long as you leave plenty of swimming space, and be sure to perform a 20% water change on a weekly basis to keep the tank parameters optimal.

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