How Many Guppies In A 5 Gallon Tank? (you might be surprised!)

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A 5-gallon aquarium is suitable for a group of 4 or 5 MALE guppies. Guppies are live-bearing fish, meaning the females give birth to live, free-swimming baby fish. By keeping only male guppies in a 5-gallon aquarium there is no chance of the number of fish in the tank increasing accidentally.

Guppies are so popular at the moment. They are colorful, friendly, and very hardy. These traits make them ideal for both the new and experienced fish keepers. I have been keeping guppies for over 30 years. I have kept guppies in everything size tank from 5 gallons to 180 gallons. Being small and friendly also makes guppies suitable for small aquariums such as a 5-gallon aquarium.

How Big Do Guppies Get?

Male guppies grow to about 1.5” (3.75cm) and female guppies grow to around 2-2.5” (5 cm-6.5cm). This size difference between the two sexes is another reason you are better off only having male guppies in a 5-gallon aquarium.

Some people will quote the ‘rule’ 1” of fish per gallon of aquarium water, meaning you could have 5” worth of fish in a 5-gallon aquarium. This rule is a bit of a myth and really shouldn’t be used as a serious way to determine how many fish can go into an aquarium.

Can I Keep Female Guppies In A 5 Gallon Too?

As discussed above, female guppies grow larger than males. This means they need a little more space, but in reality, that isn’t the reason you shouldn’t keep female guppies in a 5-gallon.

The reason you shouldn’t have female guppies in a 5-gallon aquarium is that guppies are a live-bearing species of fish. This means they quickly and easily reproduce. A female guppy can have anywhere between 40 and 80 babies at any one time.

As such, if you put a male and female guppy into a 5-gallon aquarium, within 30 to 60 days you could have 40 or more guppies in 5 gallons of water. Clearly, that isn’t sustainable!

What Else Do I Need Other Than The Aquarium?

So, let’s assume you have decided to keep a group of male guppies in an aquarium, what else will you need?

Guppies are tropical fish, and as such, they need their aquarium water to stay somewhere between 74°F and 80°F (23°C and 26°C). For most of us, that means they will need an aquarium heater.

A 5-gallon guppy aquarium will also need a filter to remove fish waste. I have found a small sponge filter connected to an air pump is probably the easiest (and cheapest) way to filter a 5-gallon aquarium. A small sponge filter will set you back less than $10 and a small air pump will probably be just $10-$15.

If you are planning to add live plants to your 5-gallon aquarium you will need to purchase a light. You can pick up a small LED light designed for a 5-gallon aquarium really cheaply on Amazon.

Tips For Making A 5 Gallon Guppy Aquarium Successful

It may surprise you to learn it is actually harder to keep a 5-gallon aquarium than a 500-gallon aquarium. Essentially, the more water the aquarium holds, the more stable the environment will be. Think of it this way, tip a cap full of bleach into a 5-gallon aquarium and it will be devastating, tip the same capful into a lake and probably no one will ever notice!

To give your 5-gallon guppy aquarium the best chance of succeeding, try some or all of the following;

  • Regularly change 50% of the water – Regular water changes remove fish waste from the aquarium. The filter turns the very toxic ammonia in fish waste into the less toxic nitrate. This nitrate then has to be physically removed in the form of water changes.

  • Add live plants – Live plants help keep an aquarium in good condition by absorbing some of the fish waste. Essentially they convert fish waste into plant growth.

  • Feed good quality food – The better quality food you feed your guppies, the fewer ‘fillers’ there will be. Fillers in cheap fish food offer the fish no nutritional value, they are just there to bulk the food out.

  • Keep your filter clean – Keeping on top of your filter maintenance keeps your filter running efficiently. The more efficient the filter, the healthier the aquarium will be.

In Conclusion

Guppies are amazing fish. On the face of it, a nice small 5-gallon aquarium might seem nice and easy to take care of. In reality, such a small tank can be harder to keep stable than one ten times its size.

Stick with 4 or 5 male guppies in your 5-gallon tank and you will have enough movement and color that the aquarium never gets boring.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James

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