Aquariums, Information

How Many Fish in a 5 Gallon Tank? (Incl. Recommended Species)

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by Jason Matthews


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Beginner fish hobbyists usually take 5 gallon tanks to keep their pet fish, which is quite understandable as they are starting out.

A 5 gallon tank is easier to maintain and keeps a few fish safe in itself if taken well care of.

However, being a beginner fish hobbyist, this question must come to your mind: how many fish can you put in a 5 gallon tank?

On average, you can keep 1 to 4 fish in a 5 gallon tank if each fish is 1-inch long. Fish that grow larger than 1-inch should not be kept in a 5 gallon tank as they need more space to swim around.

That said, this article will provide more information about keeping a 5 gallon fish tank. Read on to learn more.

General Rules When Keeping Fish in a 5 Gallon Tank

Image: ID 2497381, Pixabay

Smaller tanks can generally be used to accommodate smaller fish. This is due to the fact that they produce less waste. But, larger fish need more room to swim, grow, and generate waste.

As a general rule of thumb, a 1-inch fish needs 1 gallon of water. So, if you have a 5-gallon tank, you should keep 1-4 fish that do not grow larger than 1-inch in your aquarium.

If you keep a larger fish in a 5-gallon tank, it won’t be able to stay as larger fish are more habitat towards larger water bodies.

Best Fish Species for a 5 Gallon Tank?

The best species to keep in a 5 gallon tank are:

  • Guppies
  • Neon Tetras
  • Glofish
  • Goldfish
  • Betta Fish

Let’s talk about these species in detail below.


Guppies come at the top when you talk about having a 5 gallon tank. This species is loved by aquarium hobbyists as these fish are lovely, have flowing fins and a vibrant body.

They are a wonderful starter fish for novice aquarists since they are timid, quiet, flexible, inexpensive, and simple to care for.

These species eat a variety of meals in captivity, ranging from commercial fish foods, live foods, freeze-dried foods, and frozen foods.

Neon Tetras

Neon tetras are a species of fish that can be kept in a 5 gallon tank, but they should be housed with other fish. Neon tetras are very social and will form schools with other neon tetras, but they also tend to get along with most other types of fish.


GloFish are schooling fish – preferring to be in groups. Due to their omnivorous nature, goldfish can eat a variety of foods, including flakes, pellets, fruits, and vegetables. It is ideal to use two pellets for each GloFish.


Goldfish are not as dependent on water quality as other types of fish. They also do not need high levels of oxygen or carbon dioxide (like most other freshwater fish), so it is possible to keep them in a smaller tank.

On the downside, goldfish require more maintenance than other types of fish because they require regular feedings and cleanings. This means that you should be prepared to spend more time with your pet goldfish than other types of fish.

Betta Fish

They need an intermediate level of care. Their temperaments are moderately aggressive. They eat everything and they require freshwater and tropical waters.

Your tank will have a lovely pop of color if you have one male Betta with a few cherry shrimps!

Quick Cue: While many fish become anxious if they are not housed in a group of at least six fish, certain fish are aggressive and happiest when housed alone.
Therefore, make sure you do some research on different species before you house them in your 5-gallon aquarium.

How Should You Furnish a 5-Gallon Tank?

Image: AngieJohnston, Pixabay

Furnishing a 5 gallon tank is a lot like furnishing your home: you want to make it comfortable, but also look good.

Here are some factors that you must keep in mind when furnishing your 5 gallon tank:

1.     Substrate

First, you need to think about what kind of atmosphere you want in your tank. Some tanks have a sand substrate that may be better for tropical fish.

While others have a gravel substrate that is better for more temperate fish. Make sure the substrate you are choosing is good for your fish.

2.     Plants

You’ll also need some plants in order to keep the area clean and attractive.

There are many different kinds of plants out there—some live underwater, some live on land—and it’s up to you to choose which one works best for your tank setup.

If you’re planning on having live plants, make sure they’re not toxic to your fish!

3.     Filtration

Any tank you choose must have a filtration system to keep the water clean. One must run the system through the nitrogen cycle before adding any fish to a tank. All living things leave behind waste. This waste decomposes, producing ammonia and nitrites as it deteriorates.

For fish, both of those substances are extremely toxic. The way a filtration system operates is by circulating the water inside the tank while running the contaminated water through sponges or other kinds of filter media.

Large waste particles are removed from the water by the mechanical filter media, and the biological filter media’s bacteria are also removed. This is how you keep the tank water safe for fish.

4.     Tank density

Many fish need space to move around; if the aquarium density is too high, they won’t be able to do so. That will leave them unhappy and sick.

Given that there will be a significant amount of waste in your tank, including food leftovers and fish litter, this will also cause water pollution, exposure to bacteria, and ultimately death of the fish.

Related: The best 5 gallon fish tanks for all levels of fishkeepers

Frequently Asked Questions

Is a 5-gallon fish tank good?

Although 5-gallon fish tanks may be too small for certain fish species, they work fine for others and make an excellent starter tank for anyone who wants to keep fish.

How often should you do a water change in a 5-gallon tank?

A 25% water change should be performed every two to four weeks. The fish shouldn’t be taken out during the water change process. During the water change, be careful to agitate the gravel or use a gravel cleaner.

How often should I feed my fish?

Although 5-gallon fish tanks may be too small for certain fish species, they work fine for others and make an excellent starter tank for anyone who wants to keep fish.


To conclude, we have found that the number of fish in a 5 gallon tank is 1-4 fish. If your fish are 1-inch longer, around 4 fish can happily stay in a 5 gallon tank. If you still have any questions, feel free to ask in the comments section and we’ll get back to you as soon as we can.


Jason Matthews

My name is Jason Matthews, and welcome to my website. When other kids were bragging about how their dog could sit and roll over, I was bragging about my latest Betta Fish and the cool sea castle I just added to his aquarium. 

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