When I first thought about growing my pet platies, one of the main questions that instantly popped up in my head was the number of platies I could keep in a fish tank.
Experience has made me understand that while there are no definite answers for these questions, there are still a few guidelines that will accurately estimate the number of platies in a tank.
On average, a single platyfish needs about 2 gallons of water. For instance, a fish tank of 10 gallons can hold five platies, whereas 20 gallons can hold ten. However, you must remember that the female platies are larger and require more space than male ones.
In this article, I will help you understand the calculations better to bring home your own colorful, fun platyfish. I will also give you a gist on how many platies you can keep in a fish tank of 3 to 10 gallons or more.
So, let’s get started!
What are Platy Fish?
Ask any aquarium hobbyist, and they will describe the platy as a small, beautiful variety of fish that comes in every color you can imagine! Typically, these tiny fish species are from tropical freshwater and are by far one of the most popular of their kind.
Also known as xiphophorus, these adorable little fishes are native to both North and Central America. While male platies can grow up to 1.5 inches in size, female platies are larger and can grow up to 2.5 inches!
Of all the things that platyfish like to do, breeding is the most common. Unlike African Cichlids, usually, platies are not very aggressive fish. However, I learned that male fishes could overwhelm the females if the ratio between the two is not balanced.
They also usually roam around in small groups and are very active within their groups. Most of the time, you can find these cute little things quickly swimming in the aquarium or playing a game of hideandseek behind the aquarium décor.
The best part about these fish is that they can be trained to jump! You just need to make sure the tank is always covered up so that the fish don’t jump out.
Aquarium Size Guide for Platies
While many people have various theories on this, I have found that there is a general rule of thumb that needs to be followed when trying to find the right aquarium for your platies.
So if you are looking for ways to simplify the calculation process as I did, you can start by using this calculation to sort things out.
For every 2.54 cm (=1 inch) of platyfish, reserve 1 gallon.
However, you will still need to consider the average size of the fish while buying a tank. The young size of the platy is not a good indicator for how big it will get as it grows up. Moreover, it will be a waste of money as your pet platies will outgrow the tank in a few months.
Most platyfish reach their full size by six months. Therefore, calculate the size of your aquarium tank based on the size of a fullgrown platyfish.
Here is a quick example of 5 platyfish to help you understand them better:
One adult male platyfish will be 3.81 cm (=1.5 inches) approximately.
One adult female platyfish will be 6.35 cm (=2.5 inches) approximately.
So for 4 female platies and 1 male platyfish, the total will be 29.21 cm (=11.5 inches.)
Therefore, the minimum size of your aquarium tank should be 45.42 liters or 12 gallons.
When you’re doing calculations, this is a great tool for beginners. But there are other factors that should be considered as well to get the best accuracy. The calculation will have to be further adjusted if you plan on having all female or all male platies in a tank. This is because of the difference in size between the genders.
For instance, one of my pet male platy grew to be the same size (or almost) as my female platy fish. This goes to show that even the sizes mentioned in this article are an average estimate and are not a definite certainty.
Therefore, be extremely generous while brainstorming the calculations for the minimum tank size. However, if you are not a big fan of math, it can be pretty difficult to do these calculations. That is why I have included this table to make things easier on your end! You can use it as a quick reference.
How Many Platies In A Tank?
Size of the Tank  Number of Platy Fish 

3 Gallon  2 male, or 1 female 
5 Gallon  3 male, or 2 female 
10 Gallon  6 male, or 4 female 
20 Gallon  13 male, or 8 female 
30 Gallon  20 male, or 12 female 
40 Gallon  26 male, or 16 female 
55 Gallon  36 male, or 22 female 
60 Gallon  40 male, or 24 female 
What Happens If There are Too Many Platy Fish in a Small Tank?
As I mentioned earlier, platyfish love to breed. As a result, you might end up with lots of baby platies in a short time, and this could overcrowd the tank. This might become a problem soon enough as an overcrowded platyfish tank becomes a breeding ground for diseases as well.
To avoid this, you could do the following:
 Take one entire sex back to the aquarist. For example, you can take back either all the males or the females. My aquarist was a delight to work with as they took back the fish, even though they weren’t from their store. They immediately quarantine these platies, so you don’t have to worry about diseases.
 Recalculate and get a new tank.
 Next, split the current population into the required amounts of male and female platies.
 If you want to control the population inside the tank, you can consider introducing them to predators.
What Happens If There are Fewer Platies in a Large Gallon Tank?
If there are very few platies in a single fish tank, chances are they will begin to experience developmental health issues like stunted growth and so on. This, in turn, will shorten their lifespan as well.
Moreover, platies are generally a very playful variety of fish. They roam around in groups and can often be seen playing amongst themselves. Without any interaction, your pet platies can get bored and make them lazy. Therefore, it is best advised to put them in wellbalanced groups.
Frequently Asked Questions

Is it overstocked if I have 4 platies in a 6 gallon tank?
The answer to this depends on the sex of the platyfish. A 6gallon tank can hold four male platies or two female platies.

What is the minimum size of a tank for platy fish?
The minimum tank size for platyfish is a 10gallon tank.

Can you just keep a female/male platy in a tank?
Yes, absolutely! If you would like to have a tank of just female platies or just male platies, go ahead! The problem of breeding occurs only when there is a male and female platyfish in the same tank.

Do platies need to be in groups?
While platies can live alone and enjoy their own company, they typically thrive in a group of 5. Therefore, you can introduce them into community tanks or have them as a group in a separate platies fish tank.

Can platies live in a 6 gallon tank?
Yes. As I mentioned earlier, a 6gallon fish tank can hold four male platies or two female platies.

How many platies are right for a gallon?
A 1gallon fish tank can hold 0 male platies and 0 female platies. Yes, you read that right! It is never a good idea to hold your platy in a 1gallon fish tank as the space is too little for them.

Are platies schooling fish?
Yes, platies are typically schooling fish as they can often be seen in groups of 5. They are very interactive within this group which makes them an extremely friendly type of fish.
Final Words
While platyfishes make an extremely lovable bunch of pet fishes, I have found that it is very important to put them in rightsized tanks.
Therefore, if you are considering having pet platyfish, you should have their size as your main priority while selecting a good fish tank. Additionally, I would also ask you to consider the number of females and males you would like.
If you decide to have a tank with both sexes, I recommend you favor the females more when choosing the total number of platyfish.
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