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How Many Guppies in a 20 Gallon Tank? (Explained)

You must know the rainbow fish as the most beautiful aquarium fish. It is also known as guppy fish. Mainly, this is a multi-color fish that can add new colors to your aquarium and help you to decorate the aquarium.

But the care of guppy fish has some specific criteria. Here, the tank size will play a significant role since you need to maintain a good tank environment for your guppies. You carefully need to manage the perfect team-mate for your guppies.

How many guppies in a 20-gallon tank?

Since guppies are tiny fish, you can keep 10-12 guppies in a 20-gallon tank. If you have the entire empty tank, you should consider supporting other tank mates for your guppies. It will encourage the guppies to grow naturally. You should never keep more than 10 guppies in your 20-gallon tank.

Depending on the guppies’ size, you can only keep 10 healthy or small guppies in your 20-gallon tank. They will get enough space to swim and roam around the aquarium.

If you have any issues regarding the guppy’s growth, you can change the water or diet. It’s obvious to keep the growth of your guppies.

You need to maintain another condition to using the 20-gallon tank for your guppies. If your guppies are too small, you should keep them in a five or 10-gallon tank.

It will help them to get their food quickly and keep their growth. You should avoid using a 20-gallon tank if you don’t have enough guppies.

Apart from that, you need to choose the guppy’s mate carefully. They should be calm and don’t tend to hurt your guppies. You can avoid all the aggressive tank mates and have some friendly tank mates. They will swim together and make a good environment for each other.

Fancy guppies:

10 fancy guppies can live in a 20-gallon tank freely. You can also keep them in your 10-gallon tank until they grow big and require some extra space to keep the growth.

So, the exact number of fancy guppies for your 20-gallon tank will entirely depend on its size since the guppies have three different sizes.

If the guppies are adults, you need to keep 6-8 in a single 29-gallon tank. If they are small and don’t need extra space, you may keep up to 12 fancy guppies in your 29-gallon tank. But a 10-gallon or 5-gallon tank will be perfect for small guppies.

How many male and female guppies can live in a 20-gallon tank?

One gallon of water for every one inch of guppy is the standard formula used to determine how many guppies should be added to a tank. To put it another way, a guppy two inches long requires two gallons of water.

The results of this calculation lead us to the conclusion that the optimal number of guppies that should be kept in a tank that is 20 gallons in size is somewhere around 10. After determining how many guppies should be kept in a tank with a capacity of 20 gallons, the next step is to focus on a few other issues of critical importance.

Male guppies:

In terms of the males, you could house anywhere from 12 to 13 of them in a fish tank that holds 20 gallons of water.

Female guppies:

Since females can grow up to two inches in length, this calculation suggests you could house ten of them, or even twelve if you’re an experienced breeder. One male to two females may be the best ratio to use.

Your tank may contain three males and seven females or four males with eight females.

Are 20-gallon tanks good for guppies?

The 20-gallon tanks are good for guppies. These tanks have sufficient space for every type of guppy and other fishes to mate safely.

They can swim in the long tank and will love to eat their fry. But the thing is decoration. You need to decorate your 20-gallon tank and ensure a good environment for the guppies.

Enough Space:

The 20-gallon tank is good for guppies because of enough space. There might be a scarcity of tank spaces if you use a 5 or 10-gallon tank.

When you plan to raise 10-12 guppies at a time, you must consider buying or setting up a 20-gallon tank. It will give you the best growth indeed.

Easy to Decorate:

A 20-gallon is good for guppies since you can easily decorate the entire tank. If you use a 5 or 19-gallon tank, it will not be easy to decorate the tank using various trees.

You have that flexibility in a 20-gallon tank. You can use different decorative trees and allow your guppies to eat from there.

Keep Tank-mates:

Since a 20-gallon tank will allow you to keep some other tank-mates, the 20-gallon tank is perfect for your guppies. But you cannot do that in your 10-gallon tank.

How many of these fishes with guppies can live in a 20-gallon tank?

A certain number of these fishes can live with guppies in a 20-gallon tank.

Mollies and guppies:

Mollies can be kept contentedly in a tank that is only 20 gallons long if there are only three.

You need to provide them with a tank that is at least as large as their potential height, approximately 4 inches. Mollies require a tank with a minimum of 20 gallons in size; however, as was stated previously, they will be much happier in a larger environment.

2 mollies with 4 guppies can be good to keep together.

Guppies and neon tetras:

Neon tetras require a tank of at least 15 gallons in capacity to thrive properly.

But if you’re going to keep six neon tetras, you should at least have a tank that can hold twenty gallons of water. Both neon tetras and guppies should be kept in groups of six, while guppies should be kept in three groups.

What fish can live with guppies in a 20-gallon tank?

Many types of fishes can live with guppies in a 20-gallon tank because they have the characteristics more or less the same as the guppies.

That is why they do not create any adverse conditions to stay with those fish. Here we have shared some fishes they can stay together with guppies.


Platy fish are serene and coexist well with other fish. While not thought about tutoring animal varieties, platy fish become more positive about gatherings of six. So you can keep them with the guppies easily, and it proved.


You can keep Mollies with the guppies because these species are very quiet and can quickly adapt to other fish if kept in a tank. It is the most common species that are commonly accessible in aquariums.

Cory catfish:

Cory’s have a quiet, tranquil, and non-forceful personality. Some Cory Catfish types are more modest and timid than others. So you can purchase those fishes to keep with the guppies easily.

How to set up and take care a 20-gallon guppy tank?

To set up and take care of a 20-gallon guppy tank, we must take steps that can easily adapt to the fishes. Because the fishes are generally sensitive to their surroundings, we need to take some caution. Here we have shared those necessary steps that could help you deal with them.

Clean the tank and do QC:

To set up a tank for guppies, it must be cleaned, and quality control checked at the same time.

After having this process, you need to fill your tank with water. During a tank’s purchasing time, you have to buy a heater and thermometer to keep the environment friendly with the guppies.

The tank’s temperature should stay between 72-78°F; otherwise, they feel suffocation. If the tank’s temperature crosses the maximum or minimum limit, guppies are likely to become sick.

Installing the rest equipment like a filter:

To set the tank very well, you need to choose a good quality filter.

Because filters play out various significant capacities that assist with keeping your guppy cheerful and sound, a filter can always keep the tank water clean and remove any chemically dissolvable particles that can benefit the useful bacteria.

Another particular purpose of using filters is to stimulate water flow so that the guppies can think they are in the river where the flow is likewise.

Ensure biological decoration:

To set up the tank, ensure biological decoration is another vital part for the guppies.

If they realize they are in a greenery place, they feel they are in the river. For this reason, they can easily adapt to the environment and can move with ease.

Final thoughts

You can keep 10-12 guppies in your 20-gallon tank. Apart from that, you can keep some other tank-mates with your guppies if they are non-aggressive. The exact number of guppies will depend on their size. If they are too large, you should only keep 8; otherwise, 10 would be great.