How Many Platies Can There be in a 3, 10, 15, 20, 25, or 30-Gallon Tank?

By Nadine Oraby | 2020 Update

Being a platy fish enthusiast, the desire to add more platies in my collection never ends.  But can we keep on adding more fish in the same sized tank?

Have you wondered how many platies can live inside 3, 10, 15, 20, 25, 30-gallon tank? Well, platys love moving around the tank so it should be quite spacious inside. To create an ideal environment, the ratio of one platy per 2-3 liters of water is perfect under good conditions of filtration.

Before heading towards discussing the tank size requirements for platy, we’ll learn the behavior of this divine creature of nature.

Nature of platy fish

Platy is a very vibrant and colorful fish that comes in various hues like orange, red, blue, gold and sometimes in a combination of different colors as well. Due to its friendly nature, it can also be kept along with other fish breeds. You just have to focus on establishing a suitable environment, feeding, and caring about them.

The average size of platy fish ranges from 1.5-2.5 inches. However, the size of the male platy is slightly lesser than the female platy. Since it is a very beautiful fish and is easy to keep, many aquarists love petting them in the home tank.

Platy has a very social and active nature. They are also notorious for extra (and unwanted) swift breeding. Keeping together male and female platies results in the birth of more baby platies (fry) in a really short time.

Coming from a very active breed of fish, platies require excellent tank situation to survive inside the tank happily. Keep in mind that the tank can be filled with a large number of platies after a month; the tank size must be able to accommodate all fish comfortably. In a poor tank environment, these fish are very less likely to survive.

Ideal tank size for platy

To take proper care of platy, the first thing you need for them is getting the right tank. It is requisite for many reasons, the most important one is to provide enough space for your fish to live in close-to-natural conditions. Therefore, the right tank size is the most important thing to consider for your platy.

Let’s find out an ideal number of platies which can be kept in various tank sizes:

3-gallon tank

3 gallons is basically the size of a fishbowl. This is a very small size which is extremely common and readily available in the market. You can only keep one platy fish at a time in this fishbowl of 3 gallons. This size will not be able to provide what a platy wants. First of all, keeping it in solitude will make the fish very lonely. If you keep more than one fish inside 3 gallons tank, then it would leave very little space for both of them to move. It will eventually lead your fish towards stress and exhaustion.  Surely, you want your pet fish to play and stay happy inside their home. In a little tank, they will just survive, but not live fully.

So, you should get rid of your 3-gallon tank as soon as you can and purchase a bigger sized tank if you want to keep platys and give them a good life.

10-gallon tank

In a 10-gallon tank, 3-4 platies can live comfortably. It is recommended to keep same gender platys in a 10-gallon tank. If you are putting male and female together in a 10- gallon tank, then after a month one female platy can give birth to around 8-10 new fish which will grow into adult platys within 4 months. This vicious breeding cycle goes on throughout their lifetime. That will automatically make your 10-gallon tank size too small for all of them and you will have to upgrade your tank size eventually.

15-gallon tank

The ideal number of platies you can keep in a 15-gallon tank is 6-7. There will be enough room for fish to roam around and interact with fellow fish. You also have to install plantation and decoration inside the tank to create a happy environment for your fish. That’s why a 15-gallon tank might be suitable for 5-6 fish to live among plants.

If you want your platies to breed inside a 15-gallon tank, then you can place just 1 or 2 females with male fish. Once the fry (baby platies) are produced, you can upgrade your tank or else, keep the baby platy in a new tank.

20-gallon tank

In a 20-gallon tank, you can keep a minimum of 8 and maximum of 10 platy fish. Platys are a happy fish and require ideal tank situation to stay in their best mood. You can maintain a 20-gallon tank with best filtration and installation of plants inside for fry. The ratio of male to female for 8 fish should be 1:3, that means you may keep 2 male and six females together in you 20-gallon tank.

25-gallon tank

This is a pretty reasonable big-sized tank. If you intend to keep only platy fish then you can keep around 11-12 fish inside a 25-gallon tank.  As they are live-bearers, so get ready to have a bunch of fry in few weeks. To have control over the breeding, you can keep the ratio of 1 male to 2 female.

30-gallon tank

In a 30-gallon tank, you can keep almost 15-17 platy fish together. You can also add other breeds like guppies or mollies.

If you are a beginner and are planning to breed more fish, then you may start with 2 male and 5 female platy fish and within months, they will breed almost 20 fry (baby platy) which will turn into adults within few months.

Platy Fish Care Guide (Video)

Separate tank for fry

Adult platy fish are the predators of their own babies. As they will devour their own fry, so in case you do not take precautionary measures, the survival rate of fry will be very less.

Fry have the ability to hide under plants and leaves inside the tank. So, you must install vegetation in your aquarium to provide protection for them.

Another option is to keep the fry in a separate tank. Once the fry are born, you can keep them in a separate tank until they grow big enough to protect themselves.

Cover the filter intake with sponges otherwise, the filter could suck up the newborn fry. Fluval makes a good pre-filter sponge that fits every filter.

Other tank conditions

You must keep the tank in excellent condition to maintain a healthy community. Install a filtration system inside your fish tank for regular cleaning of wastes and toxic materials like ammonia, nitrates or nitrites etc. The weekly cycling will eliminate the poisonous elements from water and keep the water clean for fish.

The ideal water conditions are almost the same for each gallon size. Following are perfect water condition for a comfortable environment inside the tank:

  • Temperature: 72-78 degrees Farenheit
  • pH: 7-8
  • Water Hardness (DH): 10-25

The key to maintaining the healthy lifestyle of platy fish in any tank size is to have a good filter. Smaller tanks get dirtier very quickly and without filtration or cycling, fish can die very quickly inside the tank.

Like all other fish, platys love rocks and forms of aquarium decoration. To recreate the natural habitat inside the aquarium, add plants and rocks which are native to South and Central America from where these fish belong. You can get the aquarium plants or decoration from any aquarist or online pet store.

Related Questions

What are the dangers my pet platy fry can face inside the tank? They could face the problems of poor water quality, larger fish hunt, filter intake etc. You can save them by covering filters with pre-filter sponges. Also, cover your vacuum endpoint with a stocking to save the fish from blowing inside the vacuum. It is better to separate the fry from adult platy.

Why do I need to change the tank water of platy fish? Water cycling is necessary to provide a clean and healthy environment for platy and other fish as well. The fish’s waste and leftover food particles can grow toxins. You have to cycle the water regularly otherwise the toxins will accumulate in the water and it will get poisonous. Toxic water also affects the fish growth and in worst-case scenario, it can kill them.

What is the breeding rate of a female platy fish? They breed like crazy once they mature. The number of fry in a single birth depends upon the age, water condition and health of female. It could give birth from 3-4 fry to 30-40 fry at once.


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