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How Many Fish in a 5 Gallon Tank

Different fish have different characteristics, some like living with others while others prefer living alone. So when it comes to how many fish you can keep in a 5-gallon tank, the first thing that matters is what kind of fish you are saving. But generally, you can save 2-4 small fish in a 5-gallon tank.

In this article, you’ll learn how to calculate the tank density, a recommended 5-gallon tank and other products from our store Petnannystore, and fish that you can keep in a 5-gallon tank.

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Does tank density matter in fish keeping?

The answer is an absolute yes. Tank density matters a lot in fish keeping. Many fish require enough space to swim around, if the tank density is too large, they can not swim freely, which will make them unhappy and suffer from illness.

Large tank density will also lead to water contamination and exposure to bacteria because there will be a lot of waste in your tank, which includes the waste produced by fish, the leftover food, and the debris of fish.

If you can’t clean the waste in time, your fish will get diseases and die soon. Thus, it will take you more time and money to maintain your fish tank if the tank density is too large.


How to calculate tank density?

First, you should know how to calculate the water volume of your fish tank. Take a 60*45*45cm fish tank as an example, assuming the water level is 40cm high, then ignore the glass premise, the water volume = 60*45*40/1000=108L. Beginners must remember this formula, learn to calculate the water volume.

Generally, for small and medium-sized fish, it’s best to stick to a rule of thumb of one inch of fish per gallon of water, this is a safer range, take the above tank as an example, the water volume 108L, then the length of the fish in the tank (excluding the tail fin) total not more than 108cm. Similarly, if your tank is only 10L water, then the total length of the fish kept should not exceed 10cm.

The above formula is suitable for small and medium-sized fish. Small fish can be increased at your discretion while medium-sized fish follow this formula. Goldfish, parrot fish and other high oxygen fish halved, large fish should depend on the type of fish to determine the feeding density.


The appropriate fish tank density

For every 2.5 cm long saltwater fish, 300 cm² of water surface area is needed; for cold water freshwater fish, 190 cm² is needed; and for tropical freshwater fish, 75 cm² is needed.

A 60 cm long and 30 cm wide tank with 1800 cm² of the water surface can keep 15 cm of saltwater fish, 23 cm of cold-water freshwater fish, and 60 cm of tropical freshwater fish. Take this 60 cm tropical freshwater fish as an example again, it can be four 15 cm fish or ten 6 cm fish, but the amount of fish over this total length is bound to survive in a less comfortable environment and the health will naturally be tested.


A recommended 5-gallon fish tank

Hygger 5-Gallon Arc-Shaped Aquarium Kit

Hygger 5-Gallon Arc-Shaped Aquarium Kit

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The Hygger 5-Gallon Arc-Shaped Aquarium Kit includes an 8-gallon glass tank and an internal power filter pump. This set includes a 3.2 watt LED lighting system and a 3D rockery mountain background. The rocks and mountains are ideal areas for fish to rest and play. The LED light has 5 settings and extendable brackets to adjust from 0 to 19 inches.

The Arc-Shaped Aquarium is part of the Hygger's New View Aquarium Kit Series and features an ultra-white glass. The water pump runs silently and is equipped with two outlets. It can also be configured to use rainwater or a duck's mouth. This set of items comes with smooth edges and a footprint of 16.5 inches x 9 inches. The aquarium is slightly taller than other kits.

The ARC-Shaped Aquarium is made of high-quality glass. The ultra-white glass is 98% light-transmitting. The LED lighting unit has 2 settings that mimic the light of the sun or moon. It also comes with a three-stage filtration system. The curved front panel is designed to allow easy access for feeding and viewing. In addition to this, the aquarium is compatible with an external filtration system.

The ARC-Shaped Aquarium is the perfect size for shrimps or a betta. The lighted surface of the water is angled, and the lid can be flipped open or closed to change the water level. A small amount of fish food will fit inside. This is a good starter kit for fish lovers.


Other recommended products

Hygger 8-Gallon Glass Aquarium Kit

Hygger 8-Gallon Glass Aquarium Kit

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If you think a 5-gallon tank is too small, you can try the Hygger 8-Gallon Glass Aquarium Kit. It is equipped with an internal power filter pump, a colored LED light, and a decorative 3D rockery mountain background.

The power filter is a super quiet and powerful filter that can be used in a low water line (about 2.5 inches). It will help maintain a clean and comfortable environment for the creatures in your tank. The colored LED light can meet the demands of both your fish and the plants. With the extendable bracket, it can be used in tanks ranging from 0-19 inches.


Hygger Automatic Aquarium Gravel Cleaner and Water Changer

Hygger Automatic Aquarium Gravel Cleaner and Water Changer

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To remove the waste and toxins in your aquarium and create a suitable home for your lovely pets, you should do tank cleaning regularly. The most important part of tank cleaning is changing the water.

So here we recommend Hygger Automatic Aquarium Gravel Cleaner and Water Changer to you. Not only can it help remove the debris hiding in the substrate but also change the dirty water in your aquarium.

This product is operated by air press rather than electric, thus, it’s safe to use. What’s more, you can connect it with the faucet, which means you don’t need to lift a heavy bucket of water back and forth while changing the water.


Hygger 007 Newly Quartz Submersible Aquarium Heater

Hygger 007 Newly Quartz Submersible Aquarium Heate

[Go for it]

If you are keeping some tropical fish in your aquarium, it’s necessary to buy a heater. Our recommendation is the Hygger 007 Newly Quartz Submersible Aquarium Heater.

This heater is quite safe to use since it has run-dry and overheat protection. When it is not fully submerged or overheating due to long time use, it will shut off automatically. And when you turn it on, it will remain in the mode you set since it has a memory function.

With a shatter-resistant design, you don’t need to worry that it will be destroyed by some feral fish. Also, you don’t need to worry that your fish will be hurt by the heater because it has an adiabatic shell.


What kind of fish is suitable for a 5-gallon tank?

There are so many kinds of fish you can keep in a 5-gallon tank, this article will list 10 of them for you.
  • Goldfish
  • Betta fish
  • Molly fish
  • Guppy fish
  • Neon Tetra
  • Scarlet Badis
  • Chili Rasbora
  • Dwarf Pea Puffer
  • Endler’s Livebearer
  • White Cloud Mountain Minnows


Related questions

1. How many goldfish in a 5-gallon tank?

Goldfish are sociable, they do not thrive unless they are kept in a group of 3 or more. But in a 5-gallon tank, the suggestion is 2-4 fish.

2. How many betta fish in a 5-gallon tank?

Betta fish are also known as Siamese Fighting fish. They are very beautiful but also aggressive, especially males. So you’d better keep one male betta with some shrimps in a 5-gallon tank to make it more ornamental.

3. How many molly fish in a 5-gallon tank?

Molly fish are easy to produce, you’d better keep just male fish or female fish because a 5-gallon tank is too small. You can keep a group of about 5 male mollies in your 5-gallon tank.

4. How many guppy fish in a 5-gallon tank?

Guppy fish are easy to produce like molly fish. My recommendation is to keep 3 male guppy fish in a 5-gallon tank because the male fish are easier to keep and more attractive.

5. How many neon tetra fish in a 5-gallon tank?

You can keep 3 neon tetra fish in a 5-gallon tank. But the neon tetra fish prefer to be kept in a group of 6, so if you want to know more about their behaviors, you may need to buy a larger tank to keep 6 of them.

6. How many fish in a 10 Gallon Tank?

For beginners, it’s best to stick to a rule of thumb of one inch of fish(small fish) per gallon of water. One inch of fish per gallon is a safe option if you’re unsure. 



Raising fish in small fish tanks, in addition to paying attention to the species, the determination of number should also consider the size of the fish tank. If the tank is small, you can not keep too many fish so that the fish have enough space to live and swim.

In addition, if the tank has good oxygen supply equipment and filtration equipment, then the number of fish can also be increased. If these are not available, it is best to keep a few fish in a tank to ensure that each fish has enough oxygen to sustain life.

Fish-farming must be scientific, the choice of the right species and the number of fish should depend on the size of the fish tank, which is the basis and key to fish-farming. A small fish tank can not keep super-sized fish, but also a large number of fish. Otherwise, the aquatic creatures will lack sufficient space for activities, and their life growth will be seriously affected.

A 5-gallon tank is a great size for an aquarium starter kit. It’s small enough so it does not take too much space, but also big enough so that you can have some fun decorating it with plants and rocks!


Related topics:

How Many Fish Should You Keep in Your Aquarium

Comments (1)

  • Mario on Jul 15, 2022

    Amazing information! I really enjoyed reading this and it was very helpful

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