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Number of Guppies vs. Tank Gallon Size [Complete GUIDE]

How many guppies in a tank

Being an aquarist, you should first have the ideal tank size sufficient for the movement and schooling of guppies.

The easily bred and most popular fish for aquariums is the Guppy fish. Luckily, guppies don’t acquire large tanks for a living but need sufficient space.

Below is some interesting discussion on how many guppies can be in a 10-gallon tank.

The number of guppies in a 10-gallon tank:

Two guppies can live in a 3-gallon tank as highly active fish. The fish will survive, but this tank size is not enough to make a happy environment. Maintaining water parameters in such a small tank is a tough job. As a thumb rule, I recommend using a 10-gallon tank and keeping one guppy per two gallons, i.e., five guppies in a ten-gallon tank.

Having 15% fewer guppies in overcrowded tanks is favorable for avoiding conflicts and stress conditions.

Water QuantityNumber of Guppies
5 gallons3
10 gallons5
20 gallons10
25 gallons12
30 gallons15
40 gallons20
Recommended tank size vs. number of guppies

The answer given above is not enough for such a broad topic.

Continue reading about how to make favorable conditions for your guppies, the male-to-female ratio in a single tank, adjusting your tank for multiple guppies, and much more.

Tank size vs. Number of guppies

  • The tank size ideally depends on the size of your fish. For example, an adult guppy fish is two-inch long. So your guppy of two inches in length would need two gallons of water.
  • A ten-gallon aquarium can comfortably hold a group of five guppies.
  • The ideal tank size for guppies is 40 gallons, which can accommodate a reasonable number of about 20 guppies along with a few more companion fish.
  • My experience indicates that a guppy can survive in a minimum of five liters of water if the parameters are taken Care of.

How many guppies are in a five-gallon tank? As I recommended keeping one guppy per two gallons, i.e., a maximum of three guppies in a five-gallon tank. If you have financial, maintenance and space issues in the home, then use a five-gallon tank, which is easy to buy and maintain and will take up significantly less space in the home.

The ideal size of tank for guppies

The ideal tank size for guppies is 40 gallons, which can accommodate a reasonable number of about 20 guppies along with a few more companion fish.

Below are some aspects you must remember when selecting the tank for your guppy hobby.

Free space:

Usually, besides the fish, an aquarium is occupied with plants, food, objects that act as hiding places for the guppies, a water filter, an air pump, and decoration material.

So you have to remember how much free space for the guppy would be available in the tank after this all stuff.

Drawbacks of small and large tanks:

In small tanks, toxins from guppy waste accumulate more rapidly, which is risky for guppy life.

While in large tanks, guppies, especially their fry, become exhausted in search of food as they swim all around the tank. Larger tanks are tough on pockets as well.

The ideal number of guppies in the tank:

One guppy per gallon is ideal for smaller tanks of less than ten gallons.

For larger tanks greater than ten-gallon, one guppy per two-gallon tank is practical, estimating five guppies per ten-gallon tank.

Male to Female Ratio in a 3-gallon and 10-gallon tank

Male Guppy-oriented 3-Gallon and 10-Gallon tank:

If one of your objectives is to make your aquarium more colorful and you have no interest in guppy breeding, you can prefer male guppies in your tank. The same rule applies; two male guppies in the three-gallon tank and a maximum of seven male guppies in the ten-gallon tank.

Both male and female guppy-oriented 10-gallon tanks:

If you want to have both sexes in your tank, you will follow the 1:2 rule. That is one male and two females i.e, In the ten-gallon tank keep a maximum of two male with four or three female because males chase the female and harass her when she is alone or one in number.

Single guppy in a tank

Guppies are schooling fish. They prefer swimming and living in the form of a group. This way, they feel safer and less stressed.

Naturally, guppies have little emotion about feeling isolated, but it does deteriorate their health compared to the guppies living in a group.

So I advise having guppies in your tank in a minimum group of five. (for that, of course, you will need a bigger tank like 10-gallons tank)

Additional Read: Do Guppies Sleep?

Only male guppies living together in the 10-gallon tank

Male guppies have competing nature. They will constantly compete for food which will cause a fight among them.

Male guppies tend to hold territorial disputes as well. If you want to avoid an unfortunate environment, you should keep female guppies with male guppies in your tank.

Pros and Cons of keeping guppies in a small VS large size Gallon tank

1. Tight space

If you live in a small house or have little space, a three-gallon tank is perfect for carrying with your guppy hobby. For large homes, a large-sized tank minimum of ten-gallon will be preferred.

2. Indoor Aesthetics

Being a colorful fish, guppy will improve your home aesthetics, and all this is set in a low space occupied.

3. Low maintenance

The significant edge of keeping guppies in a three-gallon tank is the ease of maintenance of this size. Low maintenance will lead to a pleasant environment for your guppies to dwell.

4. Aggression

A confined space cause behavioral issues like aggression in the guppy fish. Aggression towards its tank mates is a common problem that attacks other fish. This unfriendly environment inside the tank can lead to guppy death. There are no such issues in large-sized tanks.

5. Waste toxin accumulation

Due to less space, more toxins from guppy waste accumulate inside the small sized tank. These toxins disturb the water chemistry.

Dirty aquarium

6. Poor growth

The growth of guppy organs is poor due to the confinement of space. They can’t swim freely because poor growth leads to organ failure and premature death.

Keeping guppies in a glass bowl

  • Glass bowls look pleasant aesthetically, but these bowls carry only 2-Gallons of water, which is not sufficient space for a guppy to enjoy a happy environment.
  • If even you buy a filter for your glass bowl, it will be useless because it will not get fixed inside the bowl, and limited features will not allow the filter to work correctly.

Taking Care of the guppies in a 10-gallon tank

A 10-gallon tank is comparatively a large tank. So to keep your guppies alive and happy, you need to take good Care of the tank/water parameters.

1. Plantation

Make sure you have enough plants in your tank to absorb the carbon dioxide, nitrate, and other substances that are toxic waste from the fish excretion.

Guppies can survive on their own with just plants and pests. So plantation in the ten-gallon tank is essential.

Plants in Aquarium

2. Water Quality Check

Change the water frequently to eliminate all the toxins. If you have a filter, change the water weekly.

If you do not have a water filter, about 40% of the tank water should be changed daily.

3. Feeding Habit

When feeding your guppies, try not to put too much food as it can pollute the water. Stop feeding if they stop eating.

4. Water filter installation

You need a filter that will eliminate the ammonia by changing it to nitrite and then nitrite into a less toxic form called nitrate.

(Nitrates are removed when you do the water changes in the tank). This process is called the Nitrogen Cycle.

5. PH Level

Also, make sure to maintain a healthy PH level in the tank. Here is how you can naturally control the PH in your water tank.


You can house at most two guppies in a three-gallon tank. The fish will survive but won’t be over the moon.

This is because it needs balanced water surroundings, more space to swim around, and is a schooling fish.

The ideal size of tank to be used is ten-gallons tank.