How Many Guppies in a 5 Gallon Tank

Guppies are a species of small, tropical fish. They are one of the most popular species of fish owned as pets both inside and outside the U.S. Many first-time fish owners opt for the guppy as a starter fish because they are both beautiful and relatively low maintenance. 

However, just because guppies don’t need as much active care as some other species of fish doesn’t mean you shouldn’t do your due diligence in terms of researching their optimal living conditions. 

Because guppies are popular with fish-owning beginners, they are often housed in smaller, beginner-friendly tanks. 

New guppy owners often select a small, 5-gallon tank to start with, as these tend to be less expensive and lower maintenance. 

Additionally, because guppies are such small fish, a 5-gallon tank may seem like the obvious choice.

However, as with all species of fish, there is a limit to how many guppies should be kept in a 5-gallon tank, and this limit needs to be carefully adhered to in order to guarantee the best possible quality of life for your fish. 

In this article, we’ll start by providing some useful information about guppies and their living requirements before moving on to the question of exactly how many guppies should be housed in a 5-gallon tank. 

We’ll also answer some frequently asked questions surrounding this topic to help you fully prepare for responsible guppy ownership. 

All About Guppies

Guppies, as we’ve already mentioned, are small, tropical fish. They are part of the Poeciliidae family and may also be referred to as rainbow fish and millionfish. 

These fish are native to South America and the Caribbean and live in freshwater environments. 

There are around 300 types of guppy in the world, although the common guppy (or Poecilia Reticulata) is, as its name suggests, the most common species. 

Guppies can live for up to 4 or 5 years in the optimal environment and when cared for properly. 

Male guppies usually grow to a size of 0.6 inches - 1.4 inches long. Females, meanwhile, are significantly larger, growing up to 2.4 inches in length. 

Guppies are livebearing fish, meaning that they give birth to live young. These fish breed quickly and easily (hence the origin of their ‘millionfish’ nickname), so the guppy population of a tank can multiply at a very fast rate when male and female guppies are kept together. 

Female guppies can give birth to around 25 to 50 live fry at a time and are capable of reproducing every month or so. 

Being so small, guppies don’t need a huge amount of space. However, the general rule when it comes to responsible fish keeping is that a fish measuring 1 inch in size requires 1 gallon of water to itself. 

How Many Guppies Per 5 Gallons?

So, bearing in mind what we now know about guppies and their living requirements, how many guppies can be kept in a 5-gallon tank? 

The first step to working out the answer is to go by averages. According to typical measurements, the average male guppy measures 1 inch in length, while the average female will measure about 1.8 inches. 

You should always err on the side of caution with these numbers to avoid creating cramped conditions for your fish, since guppies may grow to larger sizes than expected.

Therefore, allowing for slightly larger than average growth, you could keep up to 4 male guppies or 2 female guppies in a 5-gallon tank. 

You could keep a combination of male and female guppies, although this will complicate your spatial situation slightly due to the size differences and breeding dynamics. 

If you’re combining the sexes, it’s best to keep a higher ratio of males to females. This is because male guppies are quite persistent when it comes to mating, and a single female may easily become overwhelmed by the efforts of several males. 

So, if you’re planning on keeping both male and female guppies in a 5-gallon tank, the average sizes and mating behaviours of these fish indicate that the best combination would be 2 average-sized females and 1 average-sized male guppy. 

Of course, these numbers do not account for any baby guppies that may be produced in a shared male/female environment. 

Pregnant females will need to be removed from the tank before giving birth in any case since mature guppies have an unfortunate tendency to eat both their own and other guppies’ young. 

At this point, you will need to decide whether to rehome the fry or invest in a larger tank to accommodate them once they reach maturity. 

Frequently Asked Questions

What fish can live with guppies?

This is a very common query and one that relates to the question of how many guppies can be kept in a 5-gallon tank. 

When introducing other species of fish to your tank alongside your guppies, it’s important to be sure that the fish will be able to live harmoniously together. 

Some examples of compatible companions for guppies include other small fish such as mollies, swordtails, and platies. 

However, introducing other species to your tank will mean adjusting your spatial calculations. You’ll need to find out what the average and maximum sizes of your potential guppy companions are, and factor in these measurements accordingly. 

Final Thoughts

The bottom line here is that generally speaking, 3 or 4 guppies can safely be kept in a 5-gallon tank. 

However, this estimate is variable depending on the sex and size of each individual guppy. 

A stable, non-multiplying guppy population in a 5-gallon tank should generally come to no more than 2 females or 3 males. 

When keeping both male and female guppies in a 5-gallon tank, it is advisable to keep a maximum of 2 females and 1 male.

If you want to keep other types of fish alongside your guppies, you will need to reduce the number of guppies accordingly or, alternatively, purchase a bigger tank. 

It is important to note that these figures are guidelines only. If you are advised differently by a relevant professional (for example, a marine biologist) for a particular reason, you should adhere to this advice.