How Many Neon Tetras Per Gallon Of Water? {Is My Tank Big Enough?}

Are you wondering if your tank is large enough for multiple neon tetras? Can you use a small tank or will they become stressed? In this article, we’ll try to give exact answers to make sure your neon tetras have enough room to thrive and enjoy themselves.

How Many Neon Tetras Per Gallon Of Water? Each neon tetra needs about 1-2 gallons of water. Exact water measurements depend on the size of the neon tetra.

  • 1 gallon of = 1 inch of fish. 
  • Average size of a neon tetra = 2 inches
  • A 2 inch neon tetra = 2 gallons of water

I Have a 5 Gallon Tank. How Many Neon Tetras Can I Keep?

Neon tetras like to shoal in groups and school together for protection and security. It isn’t recommend to keep 1 or 2. A 5 gallon could hold up to 5 neon tetras, but the space is still tight. Many fish keepers have done this and commented positively or negatively.

Snails could be added as tankmates in a 5 gallon tank with neon tetras. If you notice aggressive behavior such as fin nipping, you may need a larger sized tank. A 10 Gallon tank would be much better for 5-6 neon tetras.

How Many Neon Tetras Could I Keep in a 10 Gallon Tank?

The rule of thumb is 1 gallon of water for every inch of a fish. If a neon tetra is 2 inches long, the comfortable amount would be 5 neon tetras in a 10 gallon tank. Many people recommend a limit of 6.

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Even though there are exact numbers to use, your discretion and observation also counts. Look to see if your 6 neon tetras are playing peacefully.

You can also include tankmates with your neon tetras in a 10 gallon tank. Consider these options:

  • Snails
  • Guppies
  • Ghost Shrimps

How Many Neon Tetras Could I Keep in a 20 Gallon Tank?

A 20 gallon tank is more than enough room for 8-10 neon tetras. You will notice more swimming in patterns and their curiosity will take over. Neon tetras will school together if you add other tankmates.

Once neon tetras are comfortable with their tankmates, you will spread out more and swim all over the tank. You can add more tankmates and tetras such as:

  • red eye tetras
  • cardinal tetras
  • danios
  • ghost shrimp
  • cherry shrimp
  • platys
  • guppies 
  • snails
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How Do I Know If My Tank Is Too Small?

You can measure the surface area of your tank. 1 square foot of surface area can handle 1 inch of fish. Neon tetras are active swimmers. If you notice the following signs with your neon tetras, your tank might be too small.

  • sluggish swimming
  • losing color
  • fin nipping
  • bullying
  • erratic swimming
  • eating less

Overcrowding is an issue that we are trying to avoid. Neon tetras love to swim and cover every inch of your tank. Add plenty of decorations, plants, rocks as resting spaces or places for them to explore.

Should I Keep Neon Tetras In A School?

Yes. Neon tetras do not do well on their own. They prefer the security and comfort of a group. Once they are settled into your tank, they will disperse and roam around, but the school can be formed anytime they feel the need. Otherwise, neon tetras will shoal and enjoy the company of each other.

Sometimes you will notice your neon tetras establishing their pecking order with dominance and bullying. This should not last too long. Once they’ve accepted the largest or fastest neon tetras as the dominant fish in the school, then playful swimming will resume.

A school would be better at a minimum of 5-6 neon tetras. A 10 gallon tank is a good starting point.

How Many Gallons of Water Do I Need for 10 Neon Tetras?

  • 1 gallon of = 1 inch of fish. 
  • Average size of a neon tetra = 2 inches
  • A 2 inch neon tetra = 2 gallons of water

10 Neon Tetras would be most comfortable in a 20 gallon tank. The rule above isn’t set it stone. Some neon tetras are smaller than 2 inches and measuring them exactly may not be so accurate.

Observing their behavior is more important. You can look for signs of stress if the tank is too small.

  • 4 neon tetras = 5-8 gallons of water
  • 6 neon tetras = 9-12 gallons of water
  • 8 neon tetras = 13-16 gallons of water
  • 10 neon tetras = 17-20 gallons of water


We can look for exact formulas and calculations for keeping our neon tetras happy and healthy. We check water parameters which also includes the amount of water to keep each neon tetra comfortable.

Active swimmers like neon tetras need at least 2 square feet of surface area in your tank. 1 neon tetra should require 2 gallons of water. These numbers can be adjusted to suit your needs with your neon tetras to remain playful without stress.

We hope this article serves to assist and your support your decision for how many neon tetras you wish to keep and the size of the tank you should use.

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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