How to Breed and Care for Platies

Co-authored by Marshall Stephens and Kyle Hall

Last Updated: January 20, 2023 References Approved

Platy fish are easy to care for and relatively hardy, making them great fish for beginners. Unlike most fish, platy fish are actually livebearers, meaning they give birth to live fry. If you're interested in raising and breeding platy fish, all you need to do is establish a suitable habitat and feed and care for your fish properly. Once your fish are settled into their new aquarium, they'll quickly start breeding and producing fry.

Method 1

Method 1 of 3:

Setting up a Tank

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Get an aquarium tank that holds at least 29 gallons (110 L). Although platy fish don't require a lot of space, it's a good idea to get a bigger tank than you need if you plan on breeding them. That way, as your platy fish start to reproduce and the fry grow into adults, your tank won't get overcrowded. With a tank that's at least 29 gallons (110 L), you'll be able to breed your fish and take your time finding new homes for the adults without the tank getting too crowded.^{[1]
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- You can find a large aquarium tank online or at your local pet store.
- Make sure the tank you get has a secure lid on it since platy fish can jump.^{[2]
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- An overcrowded tank can make your fish stressed and more prone to fighting.
2
Line the bottom of the tank with aquarium gravel for a fish-friendly substrate. Not only will a substrate make your aquarium look better and more natural, it will also provide a surface for beneficial bacteria to grow on in the tank. For your platy fish, you can use any kind of aquarium gravel for substrate, but make sure it's clean before adding it to the tank so your fish don't get sick.^{[3]
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- To clean your aquarium gravel, rinse it in a sieve over a bucket until the water straining through the sieve runs clear.
- You can find aquarium gravel online or at your local pet store.
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3
Add plants and hiding places to the tank so your platy fish have shelter. Providing shelter is especially important when you're breeding platy fish since the young fry will need places to hide from the adults. Without enough shelter, the young fry may be eaten by your older fish. Also, your adult platy fish will enjoy having some sheltered resting places as well.
- Try to use live aquarium plants to replicate the platy fishes' natural environment.
- Include floating plants in the tank, which make great hiding places for young fry.^{[4]
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- You can purchase plastic aquarium shelters, like small plastic caves or hollowed-out logs, online or at your local pet store.
4
Set up an air-powered sponge filter in the tank to clean and aerate the water. Without a filter, the water in the aquarium will become stagnant and dirty, and there won't be enough oxygen for your platy fish to survive. However, make sure you use an air-powered sponge filter since other types of aquarium filters can suck up and kill small fry.
- You can purchase an air-powered sponge filter at your local pet store, or you can order one online.
5
Keep the tank water at 70–77 °F (21–25 °C). This is the ideal temperature range for platy fish. Attach a thermometer to the inside of the aquarium so you can monitor the temperature and make adjustments if necessary. While it shouldn't be difficult to keep the water in the tank within this temperature range, you may need to use a heater if the water is too cold.^{[5]
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- You can purchase both submersible and hang-on aquarium water heaters online or at your local pet store. Keep in mind that the larger your aquarium, the stronger of a heater you'll need.^{[6]
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- For a 29 US gal (110 L) aquarium, you'll need a heater that's between 75 and 200 watts. The colder the room that your aquarium is in, the more watts you'll need.
- If you're worried about the water in the tank being too hot, you can buy an aquarium chiller to lower the water temperature.
6
Cycle the water in the aquarium using a limited number of platy fish. Cycling an aquarium is the process of starting a natural nitrogen cycle in the tank, which helps filter out harmful ammonia that kills fish. You can cycle your tank by introducing platy fish to it (the fish will kickstart the biological process), but you should only add 1 fish for every 2–3 gallons (7.6–11.4 L) of water. Then, once the tank has cycled after about 6 weeks, you can add the rest of your platy fish.^{[7]
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- For example, if you're using a 29 US gal (110 L) tank, you would introduce 10-14 platy fish into the tank at first. Then, after around 6 weeks, you could add more fish to the tank since the water would be safe enough at that point.
- Adding too many platy fish before the tank has cycled can put stress on the fishes' bodies and potentially cause them to die.
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Maintain a 1:3 ratio of male fish to female fish to avoid potential problems. If there are too many male fish in the tank, they might start to fight over the females. Also, an abundance of male fish can stress out your female platy fish, so it's a good idea to have 3 females for every 1 male.^{[8]
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- Determine the sex of your platy fish when you're buying them and before adding them to your tank since it will be easier than doing it after they're all swimming around in the aquarium together.
Determining the sex of your platy fish: Look closely at the fin on the bottom of your platy fish. Male platy fish will have a gonopodium—a long, rod-like fin that's used for mating— that extends backward at this point. Female platy fish won't have this kind of fin.

Method 2

Method 2 of 3:

Caring for Your Platy Fish

1
Use commercial fish food for the majority of your platy fishes' diet. In the wild, platy fish eat live organisms, like worms, insects, and crustaceans, as well as some plant matter. However, in captivity, platy fish thrive on mostly commercial fish flakes or pellets. Make sure this kind of food makes up the majority of what you're feeding your fish every day.^{[9]
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- You can find commercial fish food for your platy fish online or at your local pet store.
2
Supplement your fishes' diet with occasional meat- and vegetable-based foods. In addition to commercial fish food, you can give your platy fish small amounts of meat and vegetables with their daily feedings. Just make sure these foods aren't making up the majority of their diet.^{[10]
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- For meat-based foods, try live or frozen brine shrimp, tubifex, or blood worms.
- For vegetables, try zucchini, broccoli florets, or cauliflower. Just make sure you use organic vegetables and wash them thoroughly before adding them to the tank.^{[11]
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Feed your fish a small amount of food several times a day. When you feed your platy fish, give them about as much food as they can eat within 3 minutes. If your fish aren't finishing all of the food you give them within 3 minutes, cut back on how much you're giving them at each feeding. Too much uneaten food in the tank can dirty the water and make your platy fish sick.^{[12]
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- For example, in the morning, you could feed your platy fish as much commercial fish food (and a little meat and vegetables) as they can eat within 3 minutes. Then, you could feed them the same amount again at lunch and again at dinner.
4
Replace 25% of the water every 2-4 weeks to keep the tank water clean. Replacing a quarter of the water regularly will prevent the build-up of toxins that could make your platy fish sick. It will also prevent pH changes that aren't good for platy fish. Never replace all of the water at once since it will ruin the natural nitrogen cycle that you started in the tank when you cycled it.^{[13]
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- For example, if you have a 29 US gal (110 L) tank, you would replace a little more than 7 gallons (26 L) of water every 2-4 weeks.
- Keep in mind that the more platy fish you have, the more often you should change out the water. If you have a lot of fish for the size of your aquarium, you may want to replace the water every 2 weeks, whereas if you don't have that many platy fish in your tank, you can probably get away with replacing the water once a month.

Method 3

Method 3 of 3:

Breeding Platy Fish

1
Wait for your platy fish to start breeding after introducing them to the aquarium. Platy fish are relatively easy to breed, and they don't require a lot of encouragement. As long as you introduced both male and female platy fish to the tank, they should start breeding in a short amount of time.^{[14]
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- If your platy fish don't seem to be breeding, make sure you have both male and female fish in the tank. Also, make sure your fish are healthy and that you're feeding and caring for them properly since unhealthy platy fish might not breed.
2
Check female fish for a dark spot to determine if they're pregnant. Female platy fish will develop a dark spot on their abdomen when they're pregnant. Try to get in the habit of checking your female platy fish daily for these dark spots. Then, if you discover that one of them is pregnant, write down the date so you're able to keep track of how long it's been pregnant for.^{[15]
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Wait 24-30 days for pregnant platy fish to give birth. This is the average gestation period for platy fish. If you wrote down when you first noticed your platy fish was pregnant, the fry should be born about 24-30 days from that date.^{[16]
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- If you're not keeping track of when your female platy fish get pregnant, it can be hard to estimate when they're going to give birth. However, it will always be within 30 days of when you notice they're pregnant.
- Don't worry about doing anything special for your pregnant platy fish during their pregnancy or when they give birth. As long as you're feeding and caring for them properly, the pregnancy should go smoothly.
Did you know? Platy fish can give birth to between 20 and 80 fry, so be prepared for the population in your tank to grow rapidly.
4
Separate the fry once they're born if you're worried about them being eaten. If you've provided enough hiding places in the aquarium, like shelters and floating plants, most of the fry should be able to hide from the adults as they grow. However, if you don't want any of the fry to be eaten, you may want to transfer them to a new tank or set up a breeding trap in the tank to keep them separated.^{[17]
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- You can move the mother to a separate tank before it gives birth, or you can separate the fry after.
- To move the fry, use a fishing net to scoop them out of the tank and transfer them to a new one. Depending on where the fry are hiding, you may need to scoop up a shelter or floating plant in order to catch them.
5
Feed the fry commercial baby fish food and baby brine shrimp. Baby fish food usually consists of pulverized flakes that are easy for the small fry to eat. You should also supplement their diet with baby brine shrimp, similar to how you supplement your adult platy fishes' diet.^{[18]
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- Feed the fry in small amounts several times a day like you do with your adult platy fish.
6
Sell or giveaway your platy fish as you breed them, or move them to a new tank. Since platy fish can quickly overpopulate an aquarium, it's important that you have a plan in place for what to do with the fry as they grow and mature. Platy fish fry reach sexual maturity at 4 months of age, so you'll either want to give them to someone else or move them to their own tank before they reach 4 months. Otherwise, your tank will quickly become overcrowded, and your fish will suffer and get sick.
- Consider selling your platy fish fry and turning it into a small side business. Or, you can give them to friends who are also aquarium enthusiasts.

Community Q&A

Question

What are the signs that a Platy is ready to give birth?

Community Answer

When some females are close to giving birth, they will sometimes try to hide behind plants. Sometimes they will stay in one spot and shake/quiver for a few seconds. These are contractions. If you notice that she looks all of a sudden very plump and like she's about to pop, it's because she is!
Question

Why is my platy's color changing?

Community Answer

Depending on the color, it could be due to either stress or a change in the dominance of your tank. If the color is fading, your fish is stressed. If the color is turning more vibrant, your fish is gaining more dominance in the tank.
Question

After birth, approximately what percentage of the fry will survive and grow to the size that you would purchase at the pet store?

Community Answer

There is not an exact percentage, but about 80% should survive. To give them away at the pet store, they should be 3-5 months old. Remember to separate the fry from the other fish to avoid being eaten.