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

Neon tetras are one of the most popular fish in the hobby, and not without good reason. They look great – but they do have limits to how small of an aquarium you can keep them in.

Neon tetras can be kept in a 5 gallon aquarium, but it is recommended to keep them in at least a 10 gallon aquarium. You can keep 4-5 tetras in a 5 gallon, but neon tetras should be kept in at least groups of 6, which would require a 10 gallon tank to do.

Still, because you can keep neon tetras in a 5 gallon, I’m going to assume you will keep neon tetras in a 5 gallon, and I’m going to write this guide to tell you how to do that as successfully as possible.

I’m also going to tell you the best species of neon tetra (yes there are more than one) to keep in a 5 gallon aquarium.

Neon Tetras | Source: Deposit Photos

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

You can keep up to 5 neon tetras in a 5 gallon aquarium. A better number to keep in a 5 gallon aquarium may be 4, however, to reduce waste production in the tank. This is not ideal, as Neon Tetras should be kept in groups of 6+, but it can be done successfully.

Ideally, you should upgrade to a 10 gallon tank, which doesn’t use much more space than the 5, and keep 6-8 neon tetras.

If you’re stuck with a 5 gallon, however, and you’re set on neon tetras, there’s no reason you can’t give it a go. (Understanding that it will end badly if you neglect the tank at all.)

You’ll just need to follow some tips:

  • Give plenty of hiding places, as with such a small group they’ll feel less safe in your aquarium.
  • Pay close attention to water quality and doing regular water changes to keep ammonia from building up in your aquarium. Try to do at least one 50% water change weekly, or (alternatively) use test strips that check for ammonia as well as nitrite/nitrate to make sure your water quality isn’t dropping so you know when to do a water change.
  • Choose a 5 gallon that is short and wide instead of one that’s narrow and tall so your tetras have more room to swim around in.
  • Use a lot of live plants in the aquarium – preferably hardy ones that aren’t likely to die. This will help remove ammonia, nitrite, and nitrate from the water column.
  • Use filter media such as purigen and/or zeolite, which will help remove organic waste and ammonia respectively from your water column.

It’s still going to be a tight fit, but if you’re diligent you can make it work.

Which Tetra is Best for a 5 Gallon?

There are, however, other, smaller, Tetra species that you could consider for a 5-gallon tank.

The best species of tetra for a 5 gallon aquarium is the ember tetra. Ember tetras are the smallest type of tetra that is commonly kept in the hobby, staying .8” or smaller. This lets you keep up to 6-7 of them in a species-only 5 gallon tank.

You would still be advised to upgrade to a 10 gallon, but ember tetras are – at least – much more suited to life in a smaller aquarium.

If you must have a neon tetra, however:

The best neon tetra for a 5 gallon aquarium is the green neon tetra. These are a different species that stays slightly smaller. They typically don’t get larger than 1”, which means they will produce less bioload than a regular tetra, which can get up to 2”.

This isn’t to say that green neons will be perfect for a 5 gallon, but they’ll be better than larger types of neon tetra.

You’ll still want to follow the advice above for how many to keep – it will just make it a bit easier for you to keep them happy and healthy.

These are the only two species of tetras that stay small enough to theoretically fit into a 5 gallon aquarium, so if you want some other options, you may want to look into rasboras (who are generally hardier anyway due to neon tetra disease).

What Tank Mates Can I Put in a 5 Gallon Aquarium With My Neon Tetras?

In general, it’s best not to put any tank mates with tetras in a 5 gallon aquarium, due to its small size. Keeping some small snails, such as ramshorn snails, pond snails, and bladder snails is perfectly fine, and they can help keep your aquarium clean and free of leftover food.

I would avoid putting any fish or shrimp in an aquarium this small that’s fully stocked with fish.

Large snails, such as mystery snails or nerite snails, are also a bit iffy and should probably be avoided as well.

Small snails, on the other hand, add very little bioload to the tank, so they are perfectly fine to add to your aquarium with your neon tetras.

These are the ones I’d recommend:

  • Pond Snails/Bladder Snails
  • Ramshorn Snails

Ramshorns come in a variety of colors and patterns, such as red, blue, brown, leopard spots, stripes, and so on. They can look quite nice, especially in a small tank.

Both they and pond snails are very hardy and will clean up leftover food as well as some algae from your aquarium.

Because of this, I do recommend them for a lot of aquariums.


You can generally add around 4-5 neon tetras to a 5 gallon aquarium. Green neon tetras are the best type of tetra for small aquariums due to their smaller size. Ember tetras are a better choice because they stay smaller than even green neons.

If you can, however, you should upgrade to a 10 gallon aquarium. You’ll have more choice, can keep more fish, and you’ll probably be happier with it in the long run.

If you do choose to keep a 5 gallon, I recommend going with one that is short and long to provide your fish as much length to swim around in as possible.

Good luck with your aquarium!