Platy fry are approximately 1/4″ to 3/8″ in length when they are born.
As tiny as they are at this stage, it’s often difficult to track them in the water, especially since they’re not exactly colorful at that age. They’ll also hide while they are still in the fry stage because they have a pretty potent “prey” instinct, which makes it even more difficult to keep track of them.
How Fast Do Baby Platies Grow?
Platies will reach their maturity and full, adult growth somewhere between 3 and 6 months. Somewhere along the way, they will begin to develop their colors, part of which makes Platy fish so desirable, since they have a ton of color patterns.
There’s no real, concrete time period throughout the growth of a platy fry that can be pinpointed in terms of their colors coming in. They simply come in when they do, but you can at least expect it within that 6 month period.
Roughly half of the time, you can expect their colors to come in within a month after they’re born. One thing that is known to affect the length of time it takes for their colors to come in, is their environment. This includes the water temperature and correct water parameters.
Both of those factors also affect their growth rate, along with a healthy diet, or the unfortunate event of an unhealthy diet.

What Do You with Your Baby Platy Fry
Before you do anything with your baby platy, first you have to get ready for their arrival. This is a pretty important task, especially when you consider the fact that mommy and daddy will happily swim around the tank, feasting on their young.
- Separate the pregnant mother
- Prep small, separate habitat
- Buy some false plants or a breeding trap
- Clean the smaller, transfer tank
- Separate the mom and place her back into her tank after birth
You separate the mother so that she is not affected by other fish while she goes through the process, has a little peace and quiet in her own, small tank, and it makes it easier to save the fry when the mother is the only adult fish you have to deal with.
Prepping the smaller habitat is pretty simple. All you need to do is make sure that it is a clean, hospitable environment where the platy fry can chill out and grow for a few months. You want to make sure the environmental conditions in the temporary tank match those of the old tank.
Since platy fry are hunted down and eaten by their progenitors, they have a natural instinct to run and seek safety when they are born. That’s why you want to add some plants or even a breeding trap in the new tank for them.
With that, they will have something to hide behind, giving them a sense of safety and keeping those stressors at a minimal level. Returning the mother to her own, larger house right after she gives birth will also give the Fry some relief.
Feeding the Baby Fry
Platy fry are just like other fry, their growth is related to the quality of their diet. If you want fast growth and healthy platy, stick to a solid and positive diet for the new fry. There are several things that you can feed them as well.
- The same food that you feed the adults
- Bloodworms (Freeze-dried)
- Tubifex
- Brine Shrimp
The biggest difference between the fry and the adults is that you will feed them less, but more often throughout each day. They obviously can’t consume the same amount of food that an adult can, but it’s perfectly safe to feed them the same food that you feed an adult platy.
The amount of food that you feed them is the amount of food that they will consume before they stop eating. They need to eat three times a day, so a good regimen of breakfast, lunch, and dinner at the same time, each day, is a good routine to stick with.
You’re more than welcome to crush their food up, especially fish flakes so that it’s easier for them to get ahold of and consume without issues.
Feed them a diet that varies, ensuring that they get an equal amount of proteins with their plant-based food sources. This will boost their ability to gain their colors earlier.
You’ll also want to make sure that their tank stays as clean as possible over the next few months. High levels of ammonia are harmful to platy fish and, while they might not die from consistently above-normal ammonia, it can certainly stunt their growth along with their color development.
At the very least, it will slow their maturity process down. Most aquarium experts will advise you to change 1/4 of their water every two weeks. Once they are big enough where you feel like the mother won’t attack and feast on them on sight, it’s probably safe to reintroduce them to their families in the larger tank.
Overall, caring for baby platies isn’t too labor-intensive. Just keep up with their feeding time, tank cleaning, and ensure that they have some plants or decorations to swim around. You should see them into maturity, with their colors blooming, in just a few short months.
Final Thoughts
Platy fry will reach adulthood within three to six months, which really isn’t that long as the time will fly by and, before you know it, they’ll be adults. Just remember to adequately provide for their nutritional needs and keep their tank nice and clean. Do that, and your platy fry will flourish.