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Number of Neon Tetras vs. Tank Gallon Size [Complete GUIDE]

Neon Tetra is stunning, vibrant fish that will bring lots of excitement to your aquarium. However, being an aquarist, you should have the ideal tank size for the movement and schooling of neon tetra.

Aquarists mostly get confused about how many Neon Tetras can fit in a 10-Gallon tank. Different fish have distinct behavior related to the space they are provided. Your aquarium will develop into a healthy ecosystem, and your fish will have long and fulfilling lives if you make the right decisions.

How many Neon Tetras are in a 10-gallon tank? Neon Tetras vary in size from 1.5 inches to 2 inches. If we talk about the most common 2-inch Neon Tetra, Five to six Neon Tetras can live in a 10-gallon tank as highly active fish. I recommend using a 10-gallon tank and keeping one neon tetra per two gallons, i.e., five neon tetra in a ten-gallon tank. Maintaining water parameters in small tanks is a very tough job. For the happy survival of fish, more giant tanks are recommended.

Having 15% fewer neon tetras in overcrowded tanks is favorable for avoiding conflicts and stress conditions.

Water QuantityNumber of Neon Tetras
5 gallons3
10 gallons5
20 gallons10
25 gallons12
30 gallons15
40 gallons20
Recommended tank size vs. number of neon tetras

The answer given above is not enough for such a broad topic.

Continue reading about how to make favorable conditions for your neon tetras, the male-to-female ratio in a single tank, adjusting your tank for multiple neon tetras, and much more.

Tank size vs. number of neon tetras

  • The tank size ideally depends on the size of your fish. For example, an adult neon tetra is two-inch long. So your neon tetra, two inches in length, would need two gallons of water.
  • A ten-gallon aquarium can comfortably hold a group of five neon tetras.
  • The ideal tank size for neon tetras is 40 gallons, which can accommodate a reasonable number of about 20 neon tetras, along with a few more companion fish.
  • My experience indicates that a neon tetra can survive in a minimum of five liters of water if water parameters are optimum.

How many neon tetras are in a five-gallon tank?

I recommend keeping one neon tetra per two gallons, i.e., a maximum of three neon tetras in a five-gallon tank. If you have financial, maintenance and space issues in the home, then use a five-gallon tank, which is easy to buy and maintain and will take up significantly less space in the home.

The ideal size of tank for neon tetras

How many neon tetras are in a 20 gallons tank?

The ideal tank size for neon tetras is 20 gallons, which can accommodate a reasonable number of about ten neon tetras, along with a few more companion fish.

Below are some aspects you must remember when selecting the tank for your neon tetra hobby.

Free space:

Usually, besides the fish, an aquarium is occupied with plants, food, and objects that act as hiding places for the neon tetras, a water filter, an air pump, and decoration material.

So you have to remember how much free space for the neon tetra would be available in the tank after all this stuff.

The ideal number of neon tetras in the tank:

One neon tetra per gallon is ideal for smaller tanks of less than ten gallons.

For larger tanks greater than ten-gallon, one neon tetra per two-gallon tank is practical, estimating five neon tetras per ten-gallon tank.

Male to Female Ratio in a 5-gallon and 10-gallon tank

Male Neon Tetra-oriented 5-Gallon and 10-Gallon tank:

If one of your objectives is to make your aquarium more colorful and you have no interest in neon tetra breeding, you can prefer male neon tetras in your tank.

The same rule applies; two male neon tetras in the three-gallon tank and a maximum of seven male neon tetras in the ten-gallon tank.

Both male and female neon tetra-oriented 10-gallon tanks:

If you want to have both sexes in your tank, you will follow the 1:2 rule. That is one male and two females, i.e., In the ten-gallon tank, keep a maximum of two males with four or three females because males chase the female and harass her when she is alone or one in number.

Single neon tetra in a tank

Neon tetras are schooling fish. They prefer swimming and living in the form of a group. This way, they feel safer and less stressed.

Naturally, Neon tetras have little emotion about feeling isolated, but it does deteriorate their health compared to the Neon tetras living in a group.

So I advise having Neon tetras in your tank in a minimum group of five. (for that, of course, you will need a bigger tank like a 10-gallon tank)

Only male neon tetras living together in the 10-gallon tank

Male neon tetras have competing nature. They will constantly compete for food which will cause a fight among them.

Male neon tetras tend to hold territorial disputes as well. Therefore, to avoid an unfortunate environment, you should keep female neon tetras with male neon tetras in your tank.

Pros and Cons of keeping neon tetras in a small VS large size Gallon tank

1. Tight space

If you live in a small house or have little space, a five-gallon tank is perfect for carrying with your neon tetra hobby. However, a large-sized tank minimum of ten-gallon for large homes will be preferred.

2. Indoor Aesthetics

Being a colorful fish, neon tetra will improve your home aesthetics, and all this is set in a low space occupied.

3. Low maintenance

The significant edge of keeping neon tetras in a five-gallon tank is the ease of maintenance of this size. Low maintenance will lead to a pleasant environment for your neon tetras to dwell in.

4. Aggression

A confined space cause behavioral issues like aggression in the neon tetra fish. Aggression towards its tank mates is a common problem. This unfriendly environment inside the tank can lead to neon tetra death. There are no such issues in large-sized tanks.

5. Waste toxin accumulation

Due to less space, more toxins from neon tetra waste accumulate inside the small-sized tank. These toxins disturb the water chemistry.

A dirty tank of Neon tetras

6. Poor growth

The growth of neon tetra organs is poor due to the confinement of space. They can’t swim freely because poor growth leads to organ failure and premature death.

Keeping neon tetras in a glass bowl

  • Glass bowls look pleasant aesthetically, but these bowls carry only 2 gallons of water, which is not sufficient space for a neon tetra to enjoy a happy environment.
  • If even you buy a filter for your glass bowl, it will be useless because it will not get fixed inside the bowl, and limited features will not allow the filter to work correctly.

Taking Care of the neon tetras in a 10-gallon tank

A 10-gallon tank is comparatively a large tank. So to keep your neon tetras alive and happy, you must take good care of the tank/water parameters.

1. Plantation

Make sure you have enough plants in your tank to absorb the carbon dioxide, nitrate, and other substances that are toxic waste from the fish excretion.

In the natural river, neon tetras survive with just plants and pests. So plantation in the ten-gallon tank is essential.

2. Water Quality Check

Change the water frequently to eliminate all the toxins. If you have a filter, change the water weekly.

If you do not have a water filter, about 40% of the tank water should be changed daily.

3. Feeding Habit

When feeding your neon tetras, try not to put too much food as it can pollute the water. Likewise, stop feeding if they stop eating.

4. Water filter installation

You need a filter that will eliminate the ammonia by changing it to nitrite and then nitrite into a less toxic form called nitrate.

Nitrates are removed when you do the water changes in the tank. This process is called the Nitrogen Cycle.

5. PH Level

Also, make sure to maintain a healthy PH level in the tank. Here is how you can naturally control the PH in your water tank.


You can house at most three neon tetras in a five-gallon tank. The fish will survive but won’t be over the moon.

This is because it needs balanced water surroundings and more swimming space and is a schooling fish.

The ideal tank size is no less than a ten-gallon tank.