Instead of laying eggs, female platys give birth to live young, called fry. Females do not show signs of pregnancy for two weeks after mating.
When they are pregnant, they get very fat and develop a dark on the underside called a gravid spot. If you look closely at the gravid spot, you can see the eyes of the fry inside of the mother.
How Does a Pregnant Platy Fish Look Like?
Pregnant female platys will gradually have abdomens that gradually distend. They eventually become squared off at the bottom edge. Pregnant females also develop a gravid spot or very dark spot near the anal fin. The fry makes the spot dark.
Platys do not start to show signs that they are pregnant until two weeks after they mate, which is about halfway through their pregnancies. Their abdomens start to get bigger.
It happens gradually. By about day 26, when they look very fat, the bottom of their abdomen starts losing the round look and appearing like the bottom of a square.
It’s only about 28 days from when the female platy mates to when she gives birth. Platys have been known to take as long as 35 days before giving birth.
If the platy has passed 35 days and the bottom of her abdomen is still rounded, then she probably is not pregnant, but fat.
If she is also showing alarming symptoms like refusing to eat, bulging eyes, and scales sticking out so that she resembles a pinecone with fins, it could be dropsy, which can be fatal if left untreated.
The Gravid Spot
Platys are classified as livebearers since they give birth rather than lay eggs. However, they actually form eggs and keep them inside of their bodies.
The fry gets nourishment from the eggs and not from the mother’s body through a placenta. In about 28 days, the fry hatch, with the female giving birth.
This process is called ovoviviparity. Some snakes, sharks, insects, frogs, and toads are ovoviviparous, too.
While the fry grows, they darken. The female’s abdomen stretches, and the skin gets thinner.
This makes looking inside to the fry easier. Clustered together, the fry makes a dark spot on the female called a gravid spot. This is located on the abdomen’s underside near the anal fin.
When the female is soon to give birth, you can just make out the eyes on some of the fry through the gravid spot.
If the female is already dark or black in that area, then finding the gravid spot will be difficult. However, it may appear as if she sprouts small black specks.
Just before female platys are about to give birth, their cloacas or ventral openings sometimes dilate or become shaped like a tiny pea. However, finding the cloaca on a female platy can be difficult.
It’s easier to rely on other changes in appearance and behavior to determine if she is pregnant and when she is about to give birth.
Pregnant platys change their behavior. Their appetites will greatly increase, as they are feeding for dozens.
They will also become more skittish and hide often, going to the bottom of the tank. They look for a good place to hide and give birth in order to give the fry a chance to hide before they become fish food.
Females may also start following males around. Platys tend to breed every month, provided the conditions are right.
This means females may be in the mood to mate even before they give birth.
A short time before giving birth, which may be a few days, the female will suddenly stop eating or eat far less than she had been for the previous month.
During this time of not eating, she usually produces clear or white stringy poop. Although this may look like a worm coming out of her, it’s usually normal.
Fish that do not eat for a while produce poop like this.
Warning: Platys are Cannibals
Platy fry often do not survive because they get eaten by other fish in the aquarium – or even by the fry’s parents. Female platys have no maternal instincts after giving birth.
She will eat as much fry as she can. Hence, take precautions if you’re planning to save the fry.
When the female starts showing signs of pregnancy, remove her into a separate tank at least ten gallons large. She then can be placed back into her home tank right after she gives birth.
As an alternative, place the pregnant female in a small breeder box that hangs inside of an aquarium. She can see the other fish, but they cannot get to her or the fry.
The bottom of the breeder box has thin slots where fry fall through and the female cannot get to them.
Some platy breeders frown on breeder boxes for platys since it can stress the female. If she gets too stressed, she will abort the fry before they can survive out of her body.
Other breeders argue that moving the female causes more stress than placing her in a breeding box. New breeders may have to go through trial and error to see what works best for them.
If the female is left in a community tank and you want to save the fry, there needs to be plenty of hiding places for the fry, such as live plants or breeder moss.
Otherwise, try scooping out the fry and placing them in a separate tank.
Frequently Asked Questions About How a Pregnant Platy Fish Looks Like
Do Pregnant Platys Poop White, Stringy Poop?
Ovoviviparous fish like platys will often poop clear or white, stringy poop before they give birth. Pregnant platys often pass this kind of poop up to two days before giving birth. Clear poop is a sign the platy has stopped eating, which is normal for a fish about to give birth.
Is My Platy Pregnant or Just Fat?
Pregnant platys get a gravid spot, which fat female platys tend not to do. Pregnant platys often lose their appetites when about to give birth, while fat platys never seem to lose their appetites. Pregnant platy bellies eventually turn a square shape while fat platy bellies stay round.
Why is My Male Platy Chasing My Pregnant Platy?
Female platys tend to breed right after giving birth. The male is chasing her in the hopes that he can breed with her. The fish should be separated because he can stress her and cause her to abort.
The Least You Need to Know
A pregnant platy gets a distended abdomen and a dark spot on the underside near her anal fin called a gravid spot. Her appetite increases, although it drops off soon before she gives birth.
Her abdomen takes on a squared-off appearance rather than a round one a short time before birth.
Her cloaca may dilate. She will hide more often.