How Do Swordtail Fish Mate?

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It will be an exciting moment when your Swordtail gives birth to cute baby Swordtails. But, before that, you need to bear the responsibility of your Swordtail fish mate with each other.

Your observation skills and care should be sufficient to let this exciting moment happen.

First, the male Swordtail will flare up its fin and perform a mating dance to woo its female. Moreover, the female swordtail will peck to impress the male. 

Then, the male swordtail will touch the females’ underside and rear fins to transfer the sperm. This act is quick, so you have to be on all fours with constant vigilance. 

In this article, you can find detailed information about how Swordtails mate. 

Facts Regarding How Swordtail Fish Mate

Swordtails are interesting. And by that, I mean Swordtails are livebearers.

Usually, other fish directly lay eggs. However, Swordtails directly birth their fry without laying eggs.

There are other interesting facts about Swordtails mating below.

Age For Swordtail Fish To Mate

It is said that Swordtails get pregnant soon after birth. However, that’s not the case. Swordtails are ready to give birth at 3 months, i.e. when their reproductive organs have developed.

Stores Sperm

Your female Swordtail can store sperm in her pouch for up to 6 months. Thus, she can get multiple inseminations even without any contact with a male.

Fertility Of Swordtail

Once your Swordtails are fertile, they are mostly always pregnant!

There is a common joke among fish lovers. That Swordtails are not pregnant only when they’re pregnant.

Check The Gender

To know how Swordtails mate, first you have to know who the male and the female are.  

Sexual Dimorphism

Unlike other fish species, you can easily differentiate the gender of your Swordtails.

Male Swordtails have a long sword-like fin called gonopodium. This gonopodium can grow 5 inches in length. Whereas, female Swordtails lack this sword/gonopodium.

Males are smaller as compared to females. Females are rounder too.

Through this difference, you can easily separate them into a different tank. Also, you can easily know the male to female ratio in your tank. 

Keep More Females Than Males

Before the mating act, you should maintain the male: female ratio in your tank.

More males in a tank can spike up the aggressiveness in your tank. This is because many males will try to fight for one female. And, you do not want that.

One adult male is enough to impregnate multiple female Swordtails. So, you better keep one male Swordtail with multiple female swordtails in your tank.

Watch The Swordtail Mate Behavior

The mating behavior of Swordtails is rather sweet. Let us know how Swordtails mate.

Act Before Swordtail Fish Mate

The Swordtails will lock lips as a gesture of love. This act is common in Cichlid species.

Moreover, the male Swordtail will flare up his fin to attract the female Swordtail. It is to show that he is larger than his actual size.

Studies have shown that the female Swordtail will peck the substrate, tank wall, and sometimes even the male to attract him.

Male Swimming Around Female

You might notice your male swordtail swimming excessively around the female. Even when you try to separate the male, the male is always following the female swordtail.

The male Swordtail will swim usually on the females’ side. 

The Actual Act 

This mating act is quick. So, you have to give constant attention to your tank.

First, the male Swordtail will rub his body near the female Swordtail underside and rear fin. Then, the male will deposit semen through its fin and run in the opposite direction.

How To Know If Your Swordtail Has Mated Successfully?

You will know that your Swordtails have mated once you see the signs of pregnancy in your female Swordtail.

The signs of pregnancy are gravid spot, the eye of fry, squared belly. Moreover, she will hide in a corner behind plants at the time of giving birth.  

The female will, then, bear cute little Swordtail fry directly. The duration of pregnancy is 3-4 weeks. And, she will bear around 90 babies.

Maintaining Ideal Tank Conditions For Swordtail Fish To Mate

Under good water conditions, your Swordtails breed more rapidly and happily. Let us learn about the ideal water parameters for your Swordtails.


Swordtails breed well at 78 degrees Fahrenheit. You should buy a heater and maintain this temperature.


The ideal pH is 7.2. To increase pH, you can use a bit of baking soda but please calculate the amount before keeping it in your tank.

Then, you can buy a pH paper to measure the pH.


10-15 DG is ideal for breeding by Swordtails.

Tank Size

One Swordtail needs 15 gallons of water to swim around.

For breeding, you can keep one male with 2-3 female Swordtails. So, ideally, you need a 40-gallon tank for the best breeding condition.

Keep Into Separate Tank

You can keep the glass between the male and female Swordtail for a while. This will increase the will to mate among the Swordtail.


Does Swordtail Fish Eat Their Own Babies?

Livebearer fish are notoriously famous for eating their babies. And, even though Swordtails are peaceful fish, they don’t shy away from eating their babies.

That’s why you should separate Swordtail fry from their kind soon after birth. Use a scoop net and lure the babies to another tank. 

Are Swordtail Fish Livebearers?

Unlike other fish who lay eggs, Swordtails are livebearer fish. This means that Swordtails directly give birth to their fry as a whole, without going through the egg-laying phase. 


The mating ritual of Swordtail is rather interesting. Moreover, instead of laying eggs and getting that egg fertilized, Swordtails prefer to directly birth live fry. 

I hope you now know how Swordtail fish mate.