Should You Separate A Pregnant Platy?


Mature female Platies get pregnant all the time if kept with males.  You may have had them while they were fry, or you might’ve bought an already pregnant fish.  This is possible if the pet store where you bought it from kept it in a coed tank. Regardless, if you planned this breeding or not, you wouldn’t want an injured (or worse, dead) Platy in your tank. 

It is best to keep the pregnant Platy safe whether you plan to keep the fry or not.  If she’s suffering from stress, tank mate aggression, or bullying, separate her into a breeding tank (not a breeding box) without any males.

The main purpose of separating a pregnant Platy from the rest of the fish is to ensure her safety against aggressive tank mates during her condition (and her fry if you choose to).  But if you notice that everyone is doing fine and going about their business, you may opt to leave her there in your community tank.

Male Platies are typically aggressive regardless of the status of the female (pregnant or not).  They may nip and corner her, causing stress.  But males aren’t just the dangerous ones.

How Do I Know If My Platy Fish Is Pregnant?

A female Platy is pregnant if she exhibits a rounder than usual belly with somewhat of a box shape.   She will also develop a gravid spot that gets dark and purplish as her pregnancy progresses.

When she’s about to drop fry, she will isolate herself from the rest of her tank mates into a quieter place.

Are Pregnant Platys Aggressive?

As a survival instinct, female Platies are aggressive, too.  You may notice a pregnant Platy fighting off other fish in pursuit of food.

This is normal.  Your pregnant Platy is acting out of instinct for her and her babies’ survival.

There may be consequences however, as either she or her tank mates might get injured during scuffles.

How Long Do Platy Fish Stay Pregnant?

Platies don’t stay pregnant for very long.

A pregnant Platy will carry her babies for 28 to 30 days.  They are live bearers meaning they will give birth to live young instead of eggs.

Knowing this, you have to make the important decisions of whether to move her or not and to keep the fry or not.  This will dictate your next steps.

What Do I Do With My Pregnant Platy Fish?

Most often than not, you’ll need to separate your pregnant Platy from the rest of your fish, and there are several ways to do just that.

Separate your pregnant Platy by:

  • Using a separate breeding tank
  • Using a tank divider
  • Using a breeder box
  • Keeping a heavily planted tank

The last one is technically not separating the Platy at all, but this is how pregnant fish isolate themselves in the wild. 

How Big Of A Tank Does A Platy Need?

For a pregnant Platy, a 5-gallon tank will do nicely.  It should contain clean water with the same parameters as your main tank. 

Your filter should have a low flow.  If not, it should be equipped with a piece of pantyhose or sponge to prevent the newborns from being sucked into the device.

Don’t forget to place a heater as well as some live plants to maintain the cleanliness of the water.   

Putting an Indian almond leaf is an option but not a necessity, both to give fry cover and to keep the water healthier and cleaner.

How Do You Partition A Fish Tank?

Tank dividers are available in pet stores but most fishkeepers we know don’t like them at all.  That’s because some of these dividers are sold rolled and tend to stay curved if they’re old stock.

If you’re buying a ready-made tank divider, choose the ones made of non-toxic materials and don’t have a permanent curve. 

A good DIY tank divider can also be made using non-toxic PVC mesh, canvas, or grid.  A plastic lining is required for softer material.  This device will be held in place by aquarium divider clips or suction cups on top and the substrate at the bottom.

A good lining material would be the plastic slider or binding from a typical report folder.  They are used to seal the edges of the mesh off.

DIY dividers are easier to fit in non-standard sized or shaped tanks.  Glue is safe for fish once it has dried out.

Are Breeding Boxes Good For Fish?

Using a breeding box may help, but it will vary from fish to fish.  Explore Fish World does not recommend this method as it stresses out pregnant Platies considerably.

If you use a breeding box, use caution.  You can only put a pregnant Platy in it if she’s moments away from giving birth.  Putting her in there too early will force her to spend too much time in it, stressing her out enough to make her go into labor prematurely.  This will result in loss of some or all fry.

As you can see, using a breeding box requires perfect timing in catching the Platy right before she drops her babies. 

How Long Can A Fish Stay In A Breeder Box?

As soon as the mommy Platy is done giving birth, she must be released immediately back into the main tank.

Platies are lacking in the parental instincts department.  They simply do not care for their young.  In fact, they tend to eat their fry once they’re born.

Best Live Plants For Platys?

You can opt not to bring the mommy Platy anywhere at all, but you must protect her and her fry while they’re in the community tank.

The solution is to have lots of live plants such as hornwort, duckweed, Java moss, Java fern, and/or Anubias.  These are all easy to maintain varieties for your freshwater tank.

Fish will eat anything that can fit their mouths, fry being one of them.  And it is a very common occurrence as Platies are often mainstays in huge tanks with other kinds of tropical fish. 

Live plants will give your pregnant Platy and her fry some solitude and safety from other fish.  While plastic plants may also do the job, live plants do better because they oxygenate the water and help absorb ammonia by using it as fertilizer.

Live plants also help cut down on algae by using up resources in its stead.  So unless you have a spike in ammonia levels, you won’t have to worry about an algae bloom.

But if your heart is set on a particular fancy plastic decorative plant, you can have both it and live plants side by side in your aquarium.

How Long Does It Take For A Platy To Finish Giving Birth?

If you caught the start of labor, it’s easier to tell when she’s finished.

Platy fish can take a few hours up to 3 days to finish giving birth.  You’ll know she’s done when it’s been a while since she’s popped the last fry and her stomach is considerably flat.  The top view will confirm the slimmer belly.

When Do Platies Give Birth?

Platies usually give birth at night, but it’s not impossible for them to pop out babies during the daytime.        

How Often Do Platys Reproduce?

If males and females are kept together, expect to be getting pregnant females every month or so. 

Platies are very sexually active fish as evidenced by the behavior of males.  You may even have had births before which you didn’t notice if all fry were eaten by other fish.

How Many Platy Fry Will Survive?

Keeping your fry in the community tank will surely endanger them, especially if you don’t have lots of plants for them to hide in.

In a community tank, only a couple of fry at most usually survive as they’re eaten by other fish.  In a breeding tank, the incidence of fry death is smaller, with about half of the total number of Platy fry surviving with proper care and feeding.  This is usually about 15 to 20 per batch of fry.

Can Platy Have Babies Without A Male?

Even if you separate the males, female Platies can keep the male’s sperm stored inside her for up to 6 months.   This is from a single mating alone.

So don’t be surprised if your separated Platy becomes pregnant months after her last contact with a male.

How Do I Stop My Platys From Breeding?

If you’re not into Platy breeding or not ready for it yet, keeping an all-male Platy tank is possible.  However, their highly sexual nature may result in aggression amongst them.

An all-female tank is even rarer as Platies are usually bought for their coloration.  Females are not as highly colored as males so it makes more sense to keep an all-male Platy tank instead.  I

It is possible, though, if you choose it.

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