Neon tetras are one of the preferred choices by aquarists. These colorful fish will be fantastic additions to peaceful community tanks if they receive proper care.

Distinguishing between neon tetra males and females might be daunting because of their tiny size. Yet, this article will make things simpler for you.

Let’s scroll down and explore how to tell if a tetra is male or female.

How to Tell if a Tetra Is Male or Female?

Step 1: Ensure You Get Enough Light

Turn on the aquarium hood’s light. That way, you can easily see tiny differences between your fish in the tank.

If your hood doesn’t feature a light, it is okay to enable several lights in the room where you place your aquarium.

Step 2: Pay Attention to the Size

neon tetras in tank

Neon tetra females usually are longer than tetra males

It is time to measure adult fish with each other. Neon tetra females will usually be longer than tetra males.

Hence, if you notice a tetra adult looks larger than several of the others, it is most likely a female.

Step 3:  Look at the Belly of Each Tetra

This step refers to observing the belly of each tetra.

Male stomach areas are usually less rounded than females as females’ bellies will become bloated from carrying eggs when fully grown.

Moreover, male tetras typically feature a much sleeker look than females.

 Step 4: Observe How Tetra Interact With One Another

Observing how your tetra interacts with one another also allows you to determine its gender.

If you notice some smaller individuals chasing the larger ones around the tank, the smaller ones are most likely tetra males while the larger ones are females.

What are the Differences Between Males and Females?

Important Aspect Female Neon Tetras Male Neon Tetras
The Body Shape Curved Straight
Color Less Vivid Brighter
Blue Stripe Shape Rounded Slender
Length of Fins Larger Flatter
Belly Shorter Longer

The Body Shape

body shape of neon tetra

Females have a more rounded body shape

Relying on the size of your tetras to determine their sex is difficult as their bodies are pretty tiny.

But things will be simpler when they reach adulthood as their bodies will become larger.

Male tetras feature a relatively slender body, while female tetras come with a more rounded body shape. Females also tend to look a bit longer and larger.


Both males and females feature distinctive red and blue stripes over their bodies, but males have more vibrant and vivid colors than females.

Males feature vibrant and distinctive colors to compete with each other to attract the interest of females.

Blue Stripe Shape

Neon tetras are characterized by their neon blue stripe that runs lengthwise down the bodies.

You can rely on these blue stripes to tell if your tetras are females or males.

On the male body, the blue stripe should appear relatively straight. But it will have a curved appearance on the female tetras due to their rounded body shape.

Length of Fins

Generally, males have longer anal fins and dorsal than females. It is also one of the best ways to determine the gender of your neon tetra in an aquarium.


Female tetras feature a larger belly as they’re egg spawners. A larger belly on a female tetra does not indicate pregnancy, but it is ready to spawn.

Generally, males come with longer anal fins and dorsal than females. It is also one of the best ways to determine the gender of your neon tetra.


When Should I Breed My Neon Tetras?

Neon tetras become sexually mature at four months in most instances, but we recommend avoiding breeding them at this time.

If you provide good care, you can expect your tetras to live from eight to ten years. That means they have a lot of time for breeding.

So if you want to breed your neon tetras, it’s best to wait until they reach at least ten to twelve months old.

Should I Separate Female and Male Neon Tetras?

Neon tetra fish may breed in your aquatic community, but their fry will likely survive. Their fry doesn’t even stand a chance as other fish would typically consume the eggs.

Neon tetra fish require special conditions to spawn. Specifically, these species need a pH of 5.5 to 6 to breed.

Moreover, before spawning, you may need to keep males and females tetra separately while you condition them up.

Yet, you shouldn’t be serious about keeping females and males separately in one community tank.

Female And Male Tetras: Which Live Longer?

There isn’t clear evidence showing that females live more than males.

With decent water conditions and good care, your tetras can live for ten years, regardless of sex.

How to Sex Neon Tetras at the Pet Store?

Determining the gender of neon tetras at a store is impossible. We have tried a few times but without any luck.

So if you’re buying your neon tetras from a fish store, we recommend buying at least six individuals to get both females and males.

How to Tell if Neon Tetra Is Pregnant?

You need to look at the belly of your female Neon Tetras to tell if it is pregnant.

If there is a swollen part on its belly, that means it is pregnant. In this case, its belly will be larger than usual.

The Bottom Line

Hopefully, by the end of the article, you should know how to determine the sex of your tetras.

If you have any queries, do not hesitate to leave one comment below. We would love to answer your questions. Please share this post if it was helpful to you!

Thanks for reading!

Alex is a pet freelance writer and editor with more than 10 years of experience. He attended Colorado State University, where he earned a Bachelor’s degree in Biology, which was where he first got some experience in animal nutrition. After graduating from University, Alex began sharing his knowledge as a freelance writer specializing in pets.

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