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How Many Guppies Can Live in a 5-Gallon Tank?

Guppies are a favourite freshwater fish for many aquarium hobbyists. Not only are they easy to care for but they’re also highly active and super fun to watch! They have bright, beautifully coloured scales and fins that flap like fans! Energetic yet peaceful in nature, you may be contemplating raising guppies and are wondering just how many can live in a small 5-gallon tank? Well, I have the answer for you below:

Contrary to popular belief, you can put more that 5 guppies in a 5-gallon tank. The ‘old adage’ of 1 inch of fish per every gallon of water is somewhat outdated. The determining factor is not the size but rather how well you maintain the tank. That said, it’s best to keep guppies in groups of 3 or 4 with no more than 8 or 9 in a 5-gallon tank. Any more than 10 should be kept in a 10- or even 20-gallon tank.

Now that you know it’s okay to keep 8 or 9 guppies in a 5-gallon tank, let’s take a closer look at this further and in more detail. We’ll discuss how many and what types of fish can be kept in a small tank. We’ll also explain how big guppies get and how much space they need. We’ll even explore whether it’s possible to breed guppies in a 5-gallon tank and which aquatic creatures make the best tank mates.

So, if you’re ready to learn more about keeping guppy fish in small aquariums, then let’s get to it!

How Many Fish Can I Keep in a 5-Gallon Tank?

The general rule of thumb regarding how many fish to keep in an aquarium is usually calculated as such – 1 inch of fish per gallon of water. This, however, is only a guideline. The determining factors, in fact, are the type of fish you have and how well you maintain your tank, not the size of the aquarium.

Schooling fish such as guppies, for example, need to be kept in groups. They don’t do well on their own, even in small tanks. Therefore, keeping at least 3 or 4 is recommended. You can keep up to 8 or 9, but anymore than that can lead to overcrowding and an increased risk of ammonia spikes in the water.

Larger fish, like bettas, can also be kept in a small tank but because of their size and aggressive nature, only 1 will thrive in a 5-gallon aquarium. In this case, regardless of the typical 1:1 fish-to-water ratio, you must also account for fish temperament, water parameters, and maintenance requirements.

What Can Live in a 5-Gallon Tank?

There are many different aquatic creatures that can live in a 5-gallon tank. Besides fish like guppies, bettas, gouramis, platies, and tetras, African dwarf frogs, cherry shrimp, and hermit crabs can also thrive in a small tank under the right conditions. Bottom-dwellers like cories are also a great option.

A 5-gallon tank is quite small, especially when you consider the vast amount of aquatic space available to fish born in the wild. Large lakes for freshwater fish or the ocean for saltwater fish provide plenty of room to swim, hide, and catch food.

Therefore, when stocking a 5-gallon tank, you need to consider the type of fish that can not only survive but thrive in a small aquatic environment. Even the tiniest of fish need space to move freely and explore. A tank which holds less than 5-gallons of water is not recommended (in my opinion) for any fish!

Can I Keep Just One Guppy Fish in a 5-Gallon Tank?

Guppies are a schooling fish and prefer to live in groups. While it’s okay to keep just a single guppy fish in a 5-gallon tank, it’s recommended to have at least 3 – 1 male and 2 females. This species doesn’t do well alone and needs the ‘company’ of other fish, especially its own kind.

When considering possible tank mates for guppy fish (other than more guppies) in a 5-gallon tank, think small, peaceful types like cories, molies, platies, tetras. Aquatic creatures with calm temperaments that like to stick close to substrate at the bottom make excellent aquarium companions for guppies.

Can I Breed Guppies in a 5-Gallon Tank?

If you intend to breed guppies in a 5-gallon tank, then keep just 3 (2 females and 1 male) to start. This species has an innate ability to mate and reproduce rapidly. Each breeding cycle can yield anywhere from 20 to 50 fry! At this rate, your 5-gallon tank will be overcrowded in no time.

Once your guppies start multiplying, be sure to move them to a larger 20-gallon tank. The adults can be kept in the 5-gallon aquarium temporarily – away from the fry for at least 4 months until the babies reach maturity for it’s common knowledge that guppy parents will often eat their own young.

How Big Do Guppies Get?

Guppies range in size from 1.5 centimetres (or 0.6 inches) to 6 centimetres (or 2.4 inches) long. Males are usually smaller and typically between 1.5 and 3.5 centimetres (0.6 to 1.4 inches) in length. Females can grow as large as 3 centimetres to 6 centimetres (1.2 to 2.4 inches) long.

Regardless of their small size and skittish nature, guppies need space to swim freely and explore in an aquarium. They also like live plants to nibble on and hide in. Live plants also help keep the water cleaner and are great for holding guppy eggs. For live plants to thrive, you need at least a 5-gallon tank.

How Much Space Do Guppies Need?

Fish that swim vertically, like guppies, don’t need as much space as those that swim horizontally (the opah, for example). Therefore, guppies can do quite well in smaller tanks, such as the 5-gallon size. As they’re an active fish and like to swim about, they shouldn’t be kept in an overcrowded environment.

While a 5-gallon tank is okay for 8 or 9 guppy fish, a 10- or even 20-gallon tank is better. Given how quickly they reproduce, a 5-gallon tank will be overcrowded in no time and this can cause serious health issues (even death) for fish. A bigger tank is a better investment and more appropriate in the long run.

Do Guppies Need to be Kept in Groups?

Guppies are a schooling fish that like to be kept in groups. They’re active swimmers and will often chase each around the tank. Males will wiggle their fins and swim frantically about in an effort to attract and mate with females. This is part of what makes them so fun and interesting to watch! Be careful not to overcrowd the tank, however, as this can negatively affect the health of the fish and even cause death.

They’re best kept in groups of 3 (or more) with a male-to-female ratio of 1:2, if you want them to breed. If not, then keep only 1 gender – males are preferred as they are more colorful and tend to be more active as well. It’s recommended that you keep 1 guppy fish per every gallon of water, but this is just a guideline. You can keep more if you properly maintain the tank!


To conclude, it’s okay to keep more that 5 guppies in a 5-gallon tank. The ‘rule-of-thumb’ that states 1 inch of fish for every gallon of water can be modified if you maintain the tank properly, including regular water changes, updating the filtration system, etc. It’s best to keep guppies in groups of 3 or 4 (1 male and 2 females) with no more than 8 or 9 in a 5-gallon tank.

Hopefully, this article has been of help to you. Thanks for reading. Good luck and happy fishkeeping!

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