Can Platys Breed With Swordtails?


In the ornamental pet fish trade, the purpose of creating hybrids—or crosses between two species—is to produce better offspring which carry more desirable traits.  Since ability to sell is the bottom line, fish breeders aim for rarer colors, more unique combinations, or longer fins (especially in the case of Swords). It’s normal then, that you would want to produce your own fry to take care of.  But can they breed?

Yes, since Swordtails and Platy fish come from the same family of Xephophorus, they can breed and produce viable offspring. 

In fact, almost all swordtails and platy fish being sold today are crossbreeds between the Xiphophorus helleri (the green swordtail), the Xiphophorus maculatus (the moonfish or Mickey Mouse Platy), and/or the Xiphophorus variatus (variegated platy). 

Swordtails and platy fish come from the warm waters of Central America.  They’re hardy fish that have found their way into the hearts and aquariums of hobbyists for their beautiful colors and lively behavior.  They’re very similar in a lot of ways.

The constant crossbreeding and inbreeding among the swordtails and platy fish are the reasons why we have such a variety of lively colors and prominent characteristics among these aquarium fish today.

It is very rare to find a true Xiphophorus nowadays.

Where Do Platy And Swordtail Fish Come From?

Breeding compatibility comes with species within the same family.  And platy fish and swordtails are very similar.

Platies and swordtails are both live bearers, both freshwater fish, and both from the same family: the genus Xiphophorus.  They may look different, but scientists deem them to have come from the same ancestors. 

They also have the same temperament, which means they’re compatible living in the same aquarium.

Both are also easy to care for and not picky about their food.

The mating process should be helped by human intervention, bringing the two species together in one breeding tank for exclusivity.

It might take some time for some though, but having the right conditions will help the process along.

Will A Swordtail Breed With A Platy?

In the wild, fish choose their own kind to breed as there would be no reason not to do so with the abundance of available partners.  In captivity, breeding will naturally occur if there are several males and females of the same species in one tank.

In tanks where there is a lack of available partners within the same species, a swordtail and/or a platy will choose the next best thing: a closely related species.  And given their prolific breeding behavior, the male of the two will eventually try to mate as long as both species are healthy and living in the right conditions.

This cannot be described as natural, though, since captivity in itself is considered human intervention.

In other livebearers, there have been reports of mollies and guppies mating.  This is expected since they belong to the same genus: Poeciliidae.  The problem however is that fishkeepers have reported these to have a low mortality rate and unable to reproduce.

Explore Fish World discourages the deliberate breeding of different species that will expectedly end up producing weak and sickly fry.  It also defeats the purpose of crossbreeding which is basically to produce better offspring with higher economic value and survival rate.  If this happens accidentally in your aquarium though, we encourage you to help nurture the fry as best as you can.

What Is Cross Breeding?

The term crossbreeding has often been misused especially when breeding livebearers.

Crossbreeding is the mating of two different species of animals that come from the same breeds to produce a new species with the desired characteristics from each parent.

A crossbreed is the offspring produced by this mating, with the premise that both parents are purebreds.

Since purebreds are very rare, crossbreeding is no longer applicable to breeders (unless you can get a hold of a purebred).

Swordtails and platy fish, if bred together now, wouldn’t be crossbreeding but undergoing the process of hybridization. 

What Do You Mean By Hybridization?

Hybridization is the process by which two animals, regardless if they’re the same species, breed and produce offspring.  The resulting descendants are called hybrids.

In the case of swordtails and platy fish, none of the existing adults we have today are true breeds.  They are already hybrids in themselves.

How Do You Tell The Difference Between A Male And Female Platy?

In order to select your adults you have to know how to determine the age and sex of your fish.

Female platys have rounded anal fins, while males have pointed anal fins (gonopodium) it uses for mating.  Females are usually longer than the males.

These fish are ready to breed when they reach 8 to 10 weeks old.  They can also be deemed mature when they reach a length of 20 mm or about ¾ of an inch.

How Can You Tell If A Swordtail Is Male Or Female?

Male swordtails usually have a long pointed lower fin tail which it uses to attract females.  The females don’t have this characteristic.

Female swordtails have to be about 3 months old for it to be mature enough to breed.  It would be around over an inch during this age.

How To Breed Swordtail And Platy?

There are no differences between regular livebearer breeding and crossing swordtails with platy fish.

In breeding swordtails with platy fish, there are 4 factors:

  • The water quality
  • The male to female ratio
  • Feeding
  • The breeding cage

The breeding tank is necessary for isolation as well as to let you monitor the progress of the mating. 

Most breeding tanks are not big at all. It can be a 5- or 10-gallon tank with filtration and some live plants.  Substrate is not necessary.

Water quality: Water parameters are the usual for tropical livebearers: a temperature of 74 to 82 deg F, a pH level of 6 to 7.5, and water hardness of 8 to 12 dGH.  Ammonia and nitrites should remain at 0ppm, and nitrates should be no more than 40 ppm.

An Indian almond leaf is preferred to keep the water clean especially for when the babies arrive.

The male to female ratio: The adult livebearers are then selected for the mating.  The usual pair chosen is a male platy and 2 to 3 female swordtails, expecting the resulting fry to mostly resemble the platy.  There should be no more than 1 male, since breeding tanks are usually small and controlled.  Having more males (both of which are dominant) in such a small space will trigger their aggressive behavior.

Choose the adults that have the prominent features you want in your fry.  Most breeders choose a lyre tail as it is beautiful and more desirable to most fishkeepers.  Aside from the fins, beautiful, striking colors among your adults can help you select your breeders. 

Don’t forget to choose those that look the healthiest and strongest.

Feeding: Food is important to livebearers as the adults need lots of protein to be able to produce healthy fry.  A good variety of live food, frozen food, and fish flakes can help boost their immune system and strength when offered regularly.

The breeding cage: Both swordtails and platys lack parental instincts and don’t care at all for their babies.  They don’t recognize their own fry as kin and look at them as food.  Adult fish should be separated from the fry once the little ones are born.  Otherwise, none would survive in the presence of adults.

This is the goal of the breeding cage.  Breeders use it to get a higher yield of fry per brood.  While live plants are helpful, they’re not foolproof.

You may use a breeding cage purchased from any fish pet store for this purpose.  Make sure it’s not too small that your fish will get stressed.  The cage can be as wide as the breeding tank and half as shallow.

You can also make your own out of a sturdy frame and some aquatic or PVC mesh.  Some people use a plastic colander bought from the dollar store.  Anything will actually do as long as it won’t hurt your fish and has holes wide enough for the fry to pass through. 

Just avoid materials that may hurt, entangle, or cut your fish.  Remember, the goal of the breeding cage is to save your fry and not hurt them. 

How Do You Know If A Swordtail Is Pregnant?

Leaving the female with a male in the same aquarium is almost always a guarantee that it will get gravid.  If it came from an all-female aquarium, or you reared it from the time it was a fry, it will have a gravid spot that grows more prominent as her pregnancy progresses.

Check from time to time as some fish may not take to their partners right away.  You may give it some time or change the male or one of the females if necessary.

What Is The Gestation Period Of A Swordtail?

Female swordtails stay gravid the same length of time as guppies do: 28 to 30 days, depending on the temperature of the breeding tank. Warmer temperatures speed up the process of mating, giving birth, and maturing.

It can become pregnant again within 6 months of contact with the male and give birth every 30 days.  This is because she can hold the male’s sperm in her during that length of time.

How Many Fry Do Swordtails Give Birth To?

Swordtails and platys are prolific breeders, and crossbreeding them can produce an average of 50 babies per brood.

Crosses resemble more of the platy, with some fry exhibiting some swordtail characteristics.

Are Swordtail Crosses Fertile?

Fertility is not an issue with platy-swordfish crossbreeds.

Platy-swordtail hybrids live an average of 2 to 3 years.  If well-taken care of, they will survive for as long as 5 years.

Recent Posts