How Many Neon Tetras Per Gallon – What You Need To Consider

If you’ve finally got your fish tank and you’re wondering how many neon tetras you can fit in your tank, you’ve come to the right place!

These beautiful creatures are small enough to usually be able multiple fit in any size tank, that’s why most fish keepers prefer these freshwater fish for their home aquarium. Keeping them in groups is necessary for their survival, but you must ensure that you don’t overcrowd their tank.

Tetras are popular fish among aquarium hobbyists. With origins in Africa, central america, and south america, you know these freshwater fish are hardy and can survive various conditions, even in captivity. But with their slim and small bodies, most beginner and experienced aquarists wonder how many they can fit in their fish tanks.

But you can skip searching on the internet for how many tetras you need to fit your fish aquarium because there is a simple formula to help you know the exact number that will comfortably fit your fish tank. Below is how we calculate how many neon tetras per gallon, so you don’t have to!

Formula To Calculate How Many Neon Tetras Per Gallon

When calculating the best tank size for the number of neon tetras you have, it’s best to consider their size. These fish species grow to about 1.6 inches but it’s best to size up a bit to give some wiggle room.

The rule most fish keepers use is for any fish species under 3 inches in length; they will need atleast 1 gallon of water per inch of fish. So for a neon tetra that is 1.6 inches in size, they need atleast 1.6 gallons of water. So with those calculations, if you have a 10-gallon tank, you can comfortably fit 5-6 neon tetras.

As much as these calculations are helpful, we recommend most fish keepers prefer to play it safe rather than being too exact with the measurements. Because chances are your tetra fish might grow larger than the size you expect. To be safe, it’s best to either increase the tank size by 5 gallons or go with the lower estimate of neon tetras for your fish tank.

Overview of Neon Tetras

Tetra fish are one of the best freshwater fish to own. They are beautifully attractive and easy to care for if you have just started your fishkeeping journey. Neon tetras, in specific, have a lifespan of around ten years. But that also depends on how well you feed and take care of them in your home aquarium. 

In their natural habitat, these fish thrive in thick vegetation which is why you need to ensure their tank has plenty of plants. Floating plants are also ideal because they block excess sunlight or aquarium light in their fish tank. Neon tetras prefer low light in their home.

These beautiful fish have specific requirements regarding their care. The optimum water temperature for these fish is around 74-80 degrees Fahrenheit. They are schooling fish, so they prefer to be kept with other neon tetras. This is also good for their happiness and health because they will be less stressed in their new tank environment. 

Regarding their diet, neon tetra fish love their proteins. You can feed them fish flakes, blood worms, brine shrimp, daphnia, and tubifex.

Frozen foods are the best for these fish and help them maintain their bright colors and health. Because of their small size, ensure the food you feed them is small. You can cut the bloodworms into more digestible lengths for them to enjoy.

One thing you need to consider is the filtration system in the neon tetra tank. The more neon tetras you have, the more water changes you need to do so that you ensure good water quality in your fish tank. With a good water filter, you can maintain pure water for your tetras and keep diseases away.

Other tetra fish you can keep in a fish tank with the neon tetra include black neon tetras, ember tetras, cardinal tetras, and the green neon tetra.

How Many Neon Tetras in a 5 Gallon tank?

Although a 5-gallon fish tank is small for keeping more than one neon tetra, 2-3 can comfortably fit in a nano tank this size. If you’re a beginner fish keeper, and don’t want to invest in a large tank right off the bat, a five gallon tank might be sufficient. Nano tanks also have their issues when it comes to fish keeping that you should be aware of.

Nano tanks typically require more extensive cleaning and maintenance, especially if the fish require warm water temperatures and equipment like filters and heaters to keep them comfortable. It will be challenging to keep your tetras in this tank without overstocking because they love being surrounded by plants. 

Some tips for maintaining a 5 Gallon tank include:

  • Refrain from overfeeding your fish.
  • Carry out daily and weekly water changes.
  • Adding a water heater.
  • Constantly monitoring the water parameters.
  • Adding live plants to increase the oxygen levels in the tank. 

As they grow older, you should consider getting a larger tank for your adult neon tetras. Even freshwater species like betta fish cannot survive long in a 5 gallon fish tank. 

How Many Neon Tetras in a 10 Gallon tank?

A 10-gallon tank is more spacious for 5-6 neon tetra fish. According to the formula above, you can even fit up to seven neon tetras in a 10-gallon tank. You can add other small freshwater fish if you want to add more color and make your aquarium a community tank. 10-gallon tanks can also easily fit in most locations around your home.

Whether in the sitting area or your room, if you’re a beginner fish keeper, a 10-gallon tank is your best option because it also doesn’t cost too much compared to the other fish tanks on this list. If you plan on adding more fish to this tank, you will have to increase the tank size for them to all live comfortably.

How Many Neon Tetras in a 20 Gallon tank?

Using the formula, a 20-gallon tank can fit close to 10-11 neon tetras. This number of neon tetras will ensure your tetras are comfortable and relaxed with each other.

While this school of fish will require more care and food, they are fascinating to watch. Your neon tetras will also feel more secure in a larger group. If you have the budget for it, go for a 20-gallon tank for these freshwater fish.

You can find these 20-gallon tanks in most fish stores.

It will give you ample space also to add decorations like driftwood, caves, and plants that neon tetras love. It’s also large enough to hold a sponge filter because the more neon tetras you have, the more they excrete waste.

How Many Neon Tetras in a 30 Gallon tank?

A 30-gallon tank is enough to hold 15-20 neon tetras. With this many neon tetras, you can quickly see how these fish behave in a group. Schooling fish, when in large numbers, are active and enjoy darting from one side of the tank to the other.

If you choose a rectangular tank of this size, your neon tetras will be happier with more swimming space. These fish tanks make the perfect community tanks because you can add more freshwater fish to keep this school company. Some ideal tank mates include rams, angelfish, and dwarf cichlids.

How Many Neon Tetras in a 40 Gallon tank?

20-26 neon tetras can fit in a 40-gallon fish tank. This school of fish will require more attention from you and is best for more experienced fish keepers. You might also be tempted to add larger fish species here but definitely ensure they are not aggressive to keep your tetras comfortable.

Because larger fish can quickly look at your neon tetras as food, you are endangering the entire school in the tank. These fish can get along with Mollies, Kukhli loaches, plecos, and angelfish.

How Many Neon Tetras in a 55 Gallon tank?

If you want to keep 25 to 35 neon tetras, you should get a 55-gallon tank. Despite what you might think, 55-gallon tanks are very popular among fish keepers. Most of the ones you will find are horizontal in size and slightly taller than other fish tanks.

Your neon tetras will enjoy this fish tank because of the ample space. But the bioload will be larger considering you have more fish in your tank, so you’ll need a moderate filter and at least a 25% water change weekly.

If you don’t overfeed your neon tetras, you can manage the waste and keep the water clean.

How Many Neon Tetras in a 75 Gallon tank?

This is one of the largest fish tanks you can get for your neon tetras, and they can fit 36-50 neon tetras. If you intend on showcasing this fish tank, a school of 50 neon tetras is an absolute beauty to watch with this much display of color.

Adding other fish species to this tank is a good idea, so your neon tetras aren’t bored. Find fish species that are non-aggressive and compatible with neon tetras. 


How many neon tetras can you put in a 2.5-gallon tank?

You can only keep one neon tetra in a fish tank this small, but it probably won’t be too happy. Neon tetras are schooling fish that are comfortable in groups of at least 4-6. According to the calculations above, the least you should start with is a 5-gallon tank.

Do Neon Tetras need an air pump?

No. Most neon tetras do not require air pumps in their fish tank. Air pumps help with oxygen circulation in your home aquarium. Luckily, if you don’t overstock a neon tetras tank, there will be enough oxygen in the tank for your fish. If you’re still worried, you can add aquarium plants to help increase the oxygen levels in the fish tank.

How can you tell if your neon tetra is stressed?

Something could be wrong if your neon tetra is swimming frantically, constantly hiding, and crashing at the bottom of the tank. If they also rub themselves on the decorations like rocks or gravel, they could be stressed with their environment.

Are neon tetras good for beginners?

Yes. Neon tetras are schooling fish but are ideal for beginners and experienced fish keepers. They are peaceful fish, pretty to look at, and fun for a community tank.

How do you know if your neon tetra is happy?

You can quickly tell if your neon tetra is happy if their scales are brightly colored, it actively swims in the fish tank, they eat regularly at specified times, and they do not have white spots on its body. If their fins are not torn or ragged, they are probably doing just fine and are happy with their new environment.


When keeping Neon Tetras in your home aquarium, you must ensure they are happy and peaceful. These freshwater fish are beautiful, easy to take care of, and fun to have, especially when you keep them with other friendly fish species. One of the most important considerations your should make is to keep them in groups.

If you keep one neon tetra in a 5-gallon fish tank, it will be incredibly lonely and even suffer from diseases like stress. They are schooling fish who prefer to be around other neon tetras, so you shouldn’t deny them this comfort.

With the above simple calculation, you can adequately estimate how many tetras you need for your fish tank. What’s the best size for you?

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