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Neon tetras are very active and beautiful fish that like to swim around with their buddies in groups of at least 6.

So If your thinking of keeping a school of 6 or more Neon Tetras, then a 20 gallon tank would be an excellent choice.

When you’re thinking about stocking options for your tank, you need to think about how big the Neons will eventually get.

A full-grown Neon Tetra can grow up to 1-2 inches.

Want to learn more about the Neon Tetra? Check out our Neon Tetra Care Guide.

Equipment You Might Need For Your Neon Tetra

  1. Aqua Clear – Fish Tank Filter
  2. NICREW Classic LED Aquarium Light
  3. Tetra Aquarium Heater
  4. Python Pro-Clean Gravel Washer and Siphon Kit
  5. Marina Algae Magnet Cleaner
  6. API Freshwater Master Test Kit

What Size Tank Does A Neon Tetra Need?

Now, you might be thinking that even when it is fully grown, a Neon Tetra just grows to 2 inches – why do you need a 20-gallon tank?

The tank size depends on how many Neon’s you are going to keep. If you plan on keeping about 6, then a 10-gallon could work. However, if you’re keeping 10-20 Neon Tetras, you would need a 15 or 20-gallon tank.

It’s not just the size of the fish that you need to think about when selecting the ideal tank.

Neon tetras are active fish and like to swim around the entire tank, in the plants, through the driftwood and rocks.

So you’ll need a tank that is big enough for the fish and all the decor.

Ideally, a tank of at least 10-15 gallons has enough room for your Neon’s to school, but a 20 gallon tank or a 20 gallon long would be even better.

A tank this size with a few live plants rising into the mid-level of the tank helps keep the tetras feeling safe and secure and provides more than enough room for these little fish to swim and school.

Then there’s the social aspect of your Neon Tetra.

How many fish can comfortably keep in a 20 gallon tank

When determining how many fish you can keep in any size tank, one of the most common rules is the one inch of fish per gallon rule. While this is a good starting point and might work for many small community fish such as Neon tetras, it shouldn’t be applied to larger and messier fish like Oscars, Cichlids, Goldfish.

Since we are discussing Neon Tetras, the above rule will work just fine.

Other methods to determine stocking levels include;

  • Fish weight per volume
  • Fish length to filter capacity
  • Fish length per volume or surface area

In general, all these methods have their flaws when considering large fish, messy fish, or fish with particular needs. The best thing to do is to understand each fish you intend to keep in your 20 gallon tank and what their specific needs are, where they are from and if your tank has filtration, live plants, and any other fish.

How Many Neon Tetra Fish Per Gallon?

Now let’s take a look at how many Neon Tetra you can fit in a tank so that you don’t overstock your tank.

When it comes to calculating how many fish can fit per gallon, you would be better off going with a higher estimate for an individual fish’s size.

While a Neon Tetra usually grows up to 1.5 inches, you’d still assume 2 inches to be on the safe side.

The general rule when it comes to deciding fish per gallon is that if a fish is smaller than 3 inches, a single fish will need a gallon per inch of the length of the fish.

A very conservative estimate would be that a Neon Tetra grows to a maximum of 2 inches, a 20 gallon tank allows you to keep 20/2 = 10 Neon Tetras with lots of room to spare.

You can fit in 10 Neon Tetras easily, perhaps even push it up to 20-24, but sticking to around 10-15 of these for a 20 gallon tank should be more than enough – especially if you are planning to give them company in the tank with the likes of betta or guppies.

Neon Tetras Are Schooling Fish!

So what does this mean?

Fish that school like to swim together in a coordinated effort and a group of 6 Neons will school.

How many Neon tetras in a school?

If you want to see the best the Neon has to offer, you would want to keep at least 10 of them together. If you plan on keeping them in a 20 gallon tank, you’ll be able to have a beautiful school of 16-24 fish, which would look amazing.

Neons crave being in a school, and their beauty is in their schooling.

When schooling, Neon Tetras typically swim in a more horizontal pattern, which would require more swimming room, which would make a 20 gallon a great choice and a 20 gallon long an even better option.

Check out this roundup of the 7 Best Tank Mates For Neon Tetras to give this pretty little fish some company in your tank.

Tips For Keeping Neon Tetras In A 20 Gallon Aquarium

It may seem odd to the beginner, but smaller aquariums are harder to maintain than larger ones.

That said, if you have some experience with small tanks you could keep 16-24 Neon Tetras in a 20 gallon tank as long as you keep the following things in mind:

  • Never overfeed
  • Use lots of live plants
  • Use a good filter/heater
  • Do weekly maintenance
  • Perform weekly water changes faithfully
  • Monitor the water parameters closely (things can go wrong quickly)

So Can You Keep Neon Tetras In A 20 Gallon Tank?

Let’s recap for a second:

  • Neon tetras should be kept in schools of 4-6, but 10 would be ideal. In a 20 gallon, you could keep up to 24 Neon tetras.
  • They are schooling fish that are very active, typically swimming horizontally.
  • Use plants and rocks and driftwood to provide entertainment and also provide security for these little guys.
  • Use a good small filter to keep the tank healthy and clean.

So I hope I’ve made it clear that a 20 gallon tank is an excellent option for the Neon tetra.

Can You Keep Guppies And Neon Tetras In A 20 Gallon Tank?

If there’s one aquarium fish more popular than the Neon Tetra, it is the guppy.

Peaceful, easy to take care of, and good-looking, the guppy makes an excellent tank mate for Neon Tetras.

Of course, you do need to make some considerations when you’re adding guppies with Neon Tetras in a fish tank.

Here are some tips on keeping Neon Tetras in a 20-gallon tank with guppies:

  • A 20 gallon tank can house between 10-24 Neon Tetras comfortably; do not increase the number just because the guppy is peaceful
  • If you are keeping a pair of guppies, they will breed and overpopulate the tank in a matter of months. Stick to only male guppies in the tank with your Neon Tetra Fish
  • For a 20-gallon tank, 12 Neon Tetras and six guppies will be more than enough
  • If you’re planning to raise guppy fish fry, get a separate fish tank for them because they will not be able to survive in a 20-gallon tank with so many other fish

Learn More About Neon Tetras:

How Many Neon Tetra In A 20 gallon Tank_