Why Won’t My Swordtail Give Birth? (10 Factors Stopping Swordtails From Giving Birth)

Why is my Swordtail fish not giving birth?

As a fish keeper, sometimes one of your goals is to have your fish give birth and populate your tank, which you can either sell or give away. In this article, we will be discussing why Swordtail fish won’t give birth or won’t breed. Swordtails are very active fish, they are livebearing, meaning, they don’t lay eggs, but give birth to live fish, and again thy are omnivores. So, if your swordtail seems to be pregnant for long, and it is not giving birth, or it won’t breed at all, then this article will answer your questions, so read to the end.

Why won’t my Swordtail fish give birth? Swordtail fish and other livebearing fish could stop reproducing if, there is no male around to make them fertile, if the water condition is not suitable for them, or if they are Stressed.

Livebearing fish are not like other fish that do lay eggs, they are very unique and could act weird sometimes when it comes to giving birth or reproducing.

There are many factors that could inhibit this fish from giving birth, and they are discussed below.

Why Is My Swordtail Fish Not Breeding?

Some of the reasons or factors stopping your fish from breeding or giving birth are:

1. Stress: Did you know that female livebearing fish such as the female swordtails have the right or ability to extend their gestation period?.

Well, they do. Naturally, their gestation period is 28 days but if everything is not alright, they might withhold giving birth and retain their babies in their stomachs.

This is the reason why you can see a pregnant swordtail carry her fry for a long time without giving birth.

The fact is, when they are Stressed, they won’t feel like reproducing, and even if they have already become pregnant, they will delay their delivery time.

There are many reasons why they could be stressed, some of them are, wrong water parameters, getting stressed by other tank mates, especially, from their male counterparts, small tank size, etc.

2. Lack of Males: For them to reproduce, they need the opposite sex to do that, and if they can’t find any, they won’t even get pregnant, even talk of giving birth, because they are neither asexual nor hermaphrodites.

The male swordtails have longer and more pointed tails and are smaller than the females.

So, once both genders are sexually matured, they will mate, and the females will be fertilized and get pregnant, which will make their gravid spot bloat.

Although sometimes they could give birth without the presence of a male, this is very rare, but it happens because they can store and preserve the male’s sperm in their body, which they use anytime they want to fertilize themselves to give birth.

This is why you might see your swordtail fish reproduce all alone in a tank.

3. Infertility: Did you know that animals could also suffer Infertility?, including Swordtail fish.

Well, they could, but it is very rare to see.

Infertility in fish could be a result of huge gonopodium, bacteria, diseases, etc.

The gonopodium is a primary sexual organ of a male Swordtail fish. It is the anal fin, which they use for the insemination of sperm to the females.

The organ is found in many livebearers, and it is used for sperm insemination or deposition. It is the alternative to andropodium.

An andropodium is not as advanced as a gonopodium. It looks more like a bent anal fin with some hooks attached to it. Its primary role is to grab and secure the female during insemination.

Some male swordtails could be infertile because some varieties have very enlarged fins with gonopodium that are way too long to function.

Due to their large sex organs, they are rendered infertile.

Therefore, with male species such as Lyretails, you can keep your female for as long as four years without any indication of female pregnancy.

Another factor that could cause Infertility to swordtails is the sex organs getting damaged. In such a case, the organ will lack the hold-fast mechanism hence rendering it faulty.

Such damages can be caused by injury, disease, or microscopic infection of the caudal fin as I stated above.

In the case of male swordtail infertility, you can adopt artificial insemination or replace the existing males with others.

4. Wrong Temperature: Another factor that might hinder your swordtail from giving birth or reproducing is the wrong temperature.

They are tropical fish, meaning they don’t tolerate or at least feel comfortable in cold water, so being in cold water is very likely to hinder their reproduction system and the whole body, and they might tend to extend their gestation period even if they are already pregnant.

Their ideal water temperature is 72-80°F, and anything cooler than this could be harmful to them.

So, We recommend getting a heater for them, if you happen to live in a cooler region so that you could be able to at least maintain their ideal temperature.

5. Wrong Water Parameters: The commonest factor that is preventing your fish from giving birth or reproducing is unsuitable water parameters.

You will agree with me that every aquatic animal has their ideal type of water, and when the wrong water is provided, it won’t be able to thrive very much.

Swordtails are freshwater dwellers, so they need fresh water to thrive, and also with a pH of up to 8.2.

Water Condition Hard, Alkaline water(12-30dGH).

And the temperature should not be less than 65 and should not be higher than 80°F.

Also, they need water that is free from chemicals such as ammonia, chlorine, nitrites, nitrates, etc, because these chemicals are very harmful, and could stress them to death.

This is why we always advise you to get a water testing kit and always test your water at least twice a week to know when the water is contaminated with chemicals and do a change of water if you happen to notice a rise in any of these chemicals.

Also, introducing smaller animals like Snails, that will eat all the leftover foods is very important to maintain the good water condition.

6. Sickness and Diseases: Another factor that could stop fish from reproducing is sickness.

As I mentioned above, there are some bacteria and diseases that could make the male swordtails Infertile, and could also stop the females from conceiving.

These diseases could be a result of dirty water, and infestation through other sources like introducing fish from the wild into the aquarium or it might come through the live plants or substrates, etc.

Apart from making them unable to give birth, they could also die as a result of sickness too.

7. Good water current and aeration: Another factor that could make them feel very comfortable, and could reproduce is good aeration and water current.

This is because naturally, fish do produce a lot in a suitable environment, so if the environment is right, they will reproduce.

They need enough air in their water, to breath enough oxygen, so we do recommend getting them an air pump, and also a good filter for normal water movement or current.

8. One of the many mistakes many people make is to keep them in a tank at the wrong ratio.

The recommended ratio to keep these fish is 1 male to 2 or 3 females.

This is very important because if the population of the male is much, they will turn to become aggressive, and will drag the females, thereby causing stress for them, which might eventually kill them.

So in that case, it’s either the females will die out of stress or hide to run away from them or stop mating, and even prevent themselves from giving birth even if they are already pregnant.

9. Poor Feeding: One of the things many aquarium animals have in common is, that they tend to do fine in terms of reproduction when they are well fed with good foods.

So, If they have enough food, then they will behave and be healthy to mate, and reproduce more.

But in the case they are not okay in terms of food, they will be slow to reproduce, and in some cases might not even do that at all.

Swordtails are omnivores and scavengers too, so they could eat many things, including their babies, especially when they are hungry, so provide them with foods like brine shrimps, flakes, soft vegetables, insects, etc, and feed them at least twice a day.

10. In fishkeeping, tank size matters a lot, because it could contribute to their stress or overall happiness and health, so individual swordtails need a tank size of at least 15-20 gallons, so overstocking them might easily breed depression and some health issues, which might delay their reproduction velocity.

Now you know the most likely reasons why your fish ain’t giving birth, now let’s look at some other questions you might be willing to ask that are related to swordtails giving birth.

How Many Fry Do Swordtail Fish Produce?

Swordtails are livebearing fish, they don’t produce much like their egg-laying counterparts.

The average number of fry a female swordtail could produce is 30-35, but on some occasions, they could produce up to 100 fry.

Their gestation period is 28 days, which is just a month, meaning they could be able to reproduce many times in a space of 1 year if everything goes smoothly.

Why Did My Swordtail Fish Die After Giving Birth?

Some people do say, their fish died after giving birth, if you have heard this, or you are a victim, you might want to know why, and here is why.

Swordtail fish and other livebearing fish might die after giving birth as a result of stress and poor health.

The fact is, it takes a healthy fish to reproduce very successfully because they require a lot of strength to do this, so, when a fish is not healthy or is suffering from stress, it might die in the process of giving birth.

How Often Do Swordtail Fish Have Babies?

If they are in the right condition, Swordtails could reproduce in a matter of 6 weeks. According to experts, they could reproduce again 6 months after the first birth.

Although this solely depends on their living condition, as they will thrive more and reproduce more quickly if everything is fine with them, so expect them to reproduce at least every 2 months or a month plus 2 weeks.

When To Put Pregnant Swordtail In A Breeding Box

It is a very nice idea to relocate any pregnant swordtail fish to a breeding tank or box because they do cannibalize on their offspring. So Once she is pregnant, she should be relocated to another tank, and once she delivers, she should be kept away from the offspring to prevent cannibalism.

Once you notice that the gravid spot is bloated, which means the fish is pregnant, relocate her to a breeding box before 28 days.

28 days is their gestation period, so getting her away from the community tank before their gestation period is safe.

How Old Do Swordtail Fish Have To Be To Breed?

Swordtail fish normally reach their maturity stage and become sexually active at the age of 3 months. Once they are sexually active, they could reproduce.

So, if everything goes fine, in 3 months, your Swordtails are ready to start reproducing.

Can Male Swordtails Turn Into Female?

No, swordtails are either male or female, and they stay like that till they die.

These fish are not asexual in any way, so they have the two genders differently, so each fish is either male or female, and they are born like that, they can’t alter it in any way.

So a male or a female swordtail fish can’t possibly change its gender for any reason.

Can Swordtail And Molly Fish Crossbreed?

No, despite being livebearing fish, they belong to different families, so they can’t possibly breed.

It is very possible for fish that belong to the same family to breed and maybe reproduce, but it is very rare or nearly impossible for those in different families to breed.

So, Mollies and Swordtails don’t breed.

Can Swordtails Mate With Guppies?

Both fish are livebearing.

Some experts say, they could have sex and breed.

This means, that if you have a male swordtail and a female guppy, they are very likely to mate and reproduce.

So, guppies could mate with swordtails.


If you have read this article to the end, I believe it will solve or make you understand your problems with your fish breeding. So good luck.