How to Sex Neon Tetras? Male or Female?

Determining the gender of neon tetras is crucial, if you want to breed them. Telling the sex of neon tetras is tricky, but not impossible.

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In this article I will show you the easiest way to disguise male and female neon tetra fish.

Sexing Neon Tetras

The easiest way to tell the difference between a male and female neon tetra is to compare their size.

Usually female neon tetras are bigger than males and have a more rounded belly. Male neon tetras tend to have a flat belly, but not always the case.

Neon tetras have a blue stripe on their body. This is also a good indicator of their gender.

The blue stripe on female neon tetras is curved, while males have a strait blue stripe.

Male vs Female Neon Tetra 

Male vs Female Neon Tetra

Sexing Neon Tetra Fry

To keep it short, neon tetra fry can’t be sexed until they have a certain age. Neon tetras reach sexual maturity at 4-6 months of age.

At 4 months, you can see the differences between males and females, but you can’t tell with certainty their sex.

At What Age Should You Breed Neon Tetras?

Although neon tetras will become sexually mature at 4 months, you should not breed them just yet.

With good care, neon tetras can live up to 8-10 years, so they have plenty of time for breeding.

If you plan breeding neon tetras, I recommend waiting until they become at least 10-12 months old.

How to Sex Neon Tetras at the Pet Store?

Sexing neon tetras at the pest store is almost impossible. I’ve tried a few times, but without any luck.

Usually at the pet store, you can choose from 50-100 fish. It is challenging to catch just a few of them, so selecting males and females is just impossible.

If you are buying your neon tetras from a fish store, you should buy at least a school of 6 fish, in order to get both males and females.

Should You Separate Male and Female Neon Tetras?

Unlike guppies or other live bearers, neon tetras will not overpopulate your aquarium.

Neon tetras will breed even in a community tank, but the fry will not survive. Usually the eggs will get eaten by other fish, and won’t even have the chance to hatch.

On top of that, neon tetras require special water conditions in order to spawn. They need a lower pH of about 5.5 to 6 in order to breed.

Before spawning, you might want to keep the male and female neon tetra separately, while you condition them up. But in a community tank, you should not really care about keeping males and females separately.

Male vs Female Neon Tetras – Which Live Longer?

There is no evidence whatsoever, that female tetras lives more than male tetras. With good care and adequate water conditions, tetras will live even up to 10 years, regardless their gender.

Neon Tetra Male to Female Ratio

Neon tetras should be kept in a school of at least 6 fish. You don’t really need to keep a certain male to female ratio between neon tetras, just make sure that they don’t become aggressive.

Usually neon tetras become aggressive, if they are less than 6 fish. So if you see any sign of aggression or fighting, just add a few more neon tetras, and they will be fine, whether they are males or females.


I hope, that this article was at good use and now you can also tell if a neon tetra is male or female.

If you still have any question, please leave a comment below, or if you want me to help sexing your neon tetras, send me an email through the contact form and attache a picture of your fish.

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