How Many Neon Tetras Can You Put in a 5 Gallon Fish Tank?

In Tropical Fishby PaulK

How Many Tetras Can You Put in a 5 Gallon Fish Tank

On the upside, Neon Tetras are a small community fish. They only grow to about 1.5 to 3 inches or so when fully grown. Since tetras are a schooling fish, they prefer to be in a school of other tetras. You would need at least 6 – 10 of them and that’s about the maximum you would want to stock your 5-gallon tank with.

If you want more neon tetras or you want some other tank mates, then I would up the tank size to about 10 or 25 gallons. It’s easier to care for fish with a larger tank. Keep in mind that 6 is the bare minimum for a schooling fish, so when it comes to schooling fish, the more the merrier.

Here is a list of other fish that would work well in a 5-gallon fish tank.

If you’re going with a 5-gallon tank, just make sure that you have very good filtration and lots of live plants and maybe some snails to provide a good environment for them because 5 gallons is not a whole lot of water to work with.

Check your water parameters often, because the tank can quickly become foul if not maintained.

Water parameter requirements for a Tetra:
pH: 5 – 7.5
Water temperature: 69 – 79 degrees Fahrenheit
Water hardness: 1 – 10 degrees dH
Very low nitrate level


If you follow the 1 fish per gallon rule, then for a 5-gallon tank max would be 5 or 6. In a 10 gallon tank, 10 fish. For a 25 gallon tank, 25 tetras and so on and so on. Remember that if you combine males and females they tend to reproduce. Here is more on breeding tetras.


There are basically two main types of tetras that you will see most often in pet stores. The classic neon tetra and the cardinal tetra. Neon tetra are the smaller of the two and will grow to about 1.5 inches, so would be better for a small tank. They have red and blue streaks that don’t cover the entire length of the fish. Neon tetras are very susceptible to water temperature changes, so a good heater is recommended.

The cardinal tetra looks a lot like the neon tetra, but grow a bit longer and the red and blue streaks span the entire length of the fish. Cardinal tetras are also a bit more expensive because of their superior coloration. They prefer warmer water of about 75 – 80 degrees Fahrenheit.

Black tetra are the hardiest of the tetra species so it’s okay to have on a starter tank after it’s been cycled whereas with the neon and cardinal it would not be advised to have with a new tank. Black tetra tends to grow a bit bigger in size and prefer larger schools so they are not the type of tetra you would want for a small 5-gallon tank.

The green neon tetra is a very petite little fish with a beautiful green-blue streak that looks great in a planted tank. Since they only grow to about an inch, they are a better choice for a smaller tank.

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Obviously, for a smaller tank like a 5 gallon, you would want to have smaller, tiny fish to stock it with since they don’t produce as much waste. You also want a hardy species to cope with changes in water parameters that you would get in a nano tank.

Some smaller fish like to roam and swim around more than others, so ideally you want a fish that is not a particularly fast swimmer, and is very docile in nature.

There are many ‘nano tank’ fish that are very small to micro in size and would work well with a small tank such as a 5 gallon.

Micro Rasbora – There are many different species of micro rasbora. They are very colorful and nice to look at. Very peaceful and active and tiny!

Pea Puffer – A very active tiny fish. You should only keep one in a 5-gallon tank as they can be very aggressive and don’t mix well with other species. They are fun to watch swim around.

Sparkling Gouramis – A very peaceful, docile fish. They’re also a labyrinth fish meaning they can breathe from the surface if they have to. They’re a very shy fish so you want dim lighting with lots of plants.

Otocinclus Catfish – These are good bottom dwellers. They’re an herbivorous fish that like plant food and algae, so they are good at keeping the tank clean. They’re a schooling fish so it’s preferable to have 6-10 of them.

Betta – A good one for this small of a tank is a Betta fish. Betta fish are ideal for a small tank because they’re best kept by themselves, they don’t swim very fast or far, and they don’t grow very big. If you intend on breeding them, however, you would need a larger tank.


You have to be more careful when stocking a nano 5-gallon tank because there is not much to work with. It’s best to have live plants and over filter the tank. Also, be careful not to overfeed your fish because that will cause more waste in the tank.

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