How Many Glofish Per Gallon: What Is The Healthy Number

Last Updated on 2023-05-24

If you’re wondering how many glofish you can keep per gallon, then you’ve found the right article! In this article, not only will you find out the different tank size requirements for each type of glofish, you’ll also learn what happens when the tank isn’t big enough as well as having other frequently asked questions answered such as “how many glofish can you keep in a 20 gallon tank” answered as well!

So keep reading to find out everything you need to know!

How Many Glofish Can you Keep Per Gallon?

There are many kinds of glofish, all of which are different from each other. There are glofish tetras, bettas, barbs, danios, and rainbow sharks, and they all have different needs.

As a rule “one inch of fish per one gallon of water” is a good way to figure out how many glofish you can fit in an aquarium. While it’s a good way to get a rough estimate, there is a lot of room for error. This rule also doesn’t do well for glofish species because most glofish species are active and known as schooling species.

Using the “one inch of fish per gallon” rule, you should keep one Glofish for every 2.5 gallons. But the best fish tank would be at least 20 gallons if you’re planning to keep schools of glofish in it. To keep your glofish happy and healthy, the fish tank should also have a good filter, a heater, and some aquatic plants.

How Many Gallons Do Glofish Barbs Need?

Glofish barbs are beautiful and easy to spot because their bright colors and black stripes make a nice contrast. They are very tough fish that can live in a wide variety of water conditions and can eat almost anything. They swim around the tank in groups and are always fascinating to watch as they do so.

Because they are a type of schooling fish, glofish barbs should always be kept in groups of at least six. To give six glofish barbs the best place to live, you’ll need a 20-gallon fish tank. This will allow your glofish barbs to have more room for playing and swimming around your fish tank.

If you want to keep glofish barbs, keep in mind that they chase calm and slow-moving fish around and bite their fins. No matter how many you have or how big the tank is, you should never keep glofish barbs with fish that move slowly and have long fins, like bettas and angelfish.

Also, don’t put small shrimp in the tanks of glofish barbs because they will pick on them over and over again.

How Many Gallons Do Glofish Bettas Need?

The GloFish betta is a glowing freshwater fish from the betta fish family whose genes have been changed to make them look beautiful. Even though their genes have been changed, they behave almost exactly the same as domesticated betta fish. That means that just like regular betta fish, glofish bettas can also be very aggressive.

Most of the time, glofish bettas are kept alone, so they do well in fish tanks that are at least 5 gallons. Remember that they don’t like water that is too hot or too cold or that moves quickly. Keep the temperature of your aquarium between 76°F and 80°F, and keep the water moving slowly and gently.

Male GloFish betta can become very aggressive in a community aquarium if he ever feels threatened or thinks his territory is being invaded. If you don’t want them to attack, you should be very careful when picking tankmates. Because they can be aggressive, it’s best to keep a GloFish betta in its own fish tank.

How Many Gallons Do Glofish Danios Need?

Glofish danio are pretty, modified glow-in-the-dark versions of danio rerio fish. They are active, pretty, tough, quick to adapt to new places, and easy to take care of. A full-grown Danio glofish can reach a length of 1.2 to 1.6 inches.

Using the “one inch per gallon” rule, you could technically put 4 to 5 glofish danios inside a 10-gallon fish tank. However, they are very active and need a lot of room to move around, so that rule isn’t gonna cut it. What you’ll probably need is at least a 20-gallon fish tank to keep about 6 to 8 of them.

Aside from giving fish more room, bigger fish tanks also have some other advantages. Bigger fish tanks are more stable than small fish tanks because any fluctuations will just be diluted by the large volume of water. If the water parameters aren’t stable, your glofish will get sick more and won’t grow as well.

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How Many Gallons Do Glofish Tetras Need?

GloFish Tetras are beautiful glowy fish that are calm, colorful, and easy to take care of. They are so peaceful that they can live with almost any other fish species that are not aggressive. This makes them a great first fish for people who are starting out in fishkeeping.

One thing to keep in mind is that glofish tetras need to be kept in groups of at least 5 tetras because they are basically just glow-in-the-dark versions of white skirt tetras, which are schooling fish.

Technically, 5 glofish tetras could still live in a 10-gallon fish tank, but the environment would be less stable. The best way to give them the best place to live is to put them in 20-gallon fish tanks.

Putting a school of glofish tetras in 10-gallon fish tanks doesn’t leave much room for water quality fluctuations, which can lead to stress and fighting. Also, even small changes in the quality of the water can be very bad. These, in turn, have a big effect on the fish by slowing their growth, making them more likely to get sick, and shortening their lives.

How Many Gallons Do Glofish Sharks Need?

Just like any other glofish, glofish sharks need pretty much the same care as their regular versions, (rainbow sharks). If given the proper environment and diet, a well-cared-for GloFish shark can live for up to eight years in an aquarium. A fully grown glofish shark can reach a length of about 6 inches.

GloFish Sharks are big, so a single glofish shark should only be kept in aquariums that are at least 20 gallons. They like to be alone and will even attack other fish of the same kind. But if you really want to keep a few glofish sharks together, you’ll need a larger fish tank that gives them enough space, since these fish are very territorial.

GloFish sharks are very active, bottom-dwelling fish that need a big tank with lots of room to swim. Because of this, it is often recommended that they are kept in a long, shallow tank instead of a tall one. It is also suggested that you put in a mechanical filter that moves the water well and an air pump to keep the water well oxygenated.

What’s The Best Size Tank For Glofish?

Choosing the best tank size can be very hard, especially since there are many different kinds of glofish and most of them have different needs and act in different ways. Some of them are territorial, active, and aggressive and need to be kept in large groups, while others are peaceful, calm, and shy.

They are also not all the same size, which is something that also needs to be considered when picking out the perfect tank size.

However, the fish tank that can provide adequate space and living conditions for fish would be 20 gallons. You can always put a glofish betta in any tank size that’s bigger than 5 gallons because they are content being on their own.

Glofish tetras, danios, and barbs can all live in a 20-gallon fish tank so you can keep them in large groups. Because they are active and playful, glofish danios, and barbs need a lot more space to swim around. Tetra fish are usually more calm, but they also need good, stable water quality, which is easy to keep up in larger fish tanks.

What Happens If You Put Glofish In A Tank That’s Too Small?

To keep your glofish happy and healthy, you need to give it what it needs. Your glofish needs good food and water, and it also needs a lot of space to swim. Because if you don’t, the things below could happen.

1. Glofish Grow Slowly

A small fish tank will always mean that there is less room for activity and exercise for your glofish. Most glofish species are energetic and need lots of swimming space. If they can’t move properly, it can stress them, affecting their growth rate.

2. Water Gets Polluted Easily

Small tanks are more unstable, are harder to keep clean, and can get polluted water faster. This is because smaller fish tanks have less water in them, which makes it hard to dilute any harmful substances in the water. Smaller fish tanks also need to be cleaned and have their water changed more often than larger ones.

3. Territorial Aggression

There are a lot of species of glofish that live in groups and are pretty social and friendly. But if you put too many of them in a small fish tank, they will fight among themselves. The fish, especially the males, will become more nervous and irritable because they won’t be able to swim around and claim small territories.

4. Shortened Lifespan 

Keeping a glofish in a small aquarium can cause undue stress and make it vulnerable to secondary illnesses. In turn, this will hurt the glofish’s health and could drastically shorten their lifespan. Fish that spend their whole lives in small tanks can get stunted growth, deformities, weakened muscles, and other health problems.

5. Death

If you put your glofish in a small tank, it will become stressed out all the time. Toxins in the water can stay at high levels in a small fish tank because the water doesn’t get diluted. Also, the ammonia that comes from fish poop can contaminate the whole fish tank quickly.

6. Less Oxygen

Most of the time, oxygen exchange takes place at the top of the water in your fish tank. When you have a small fish tank, there will be less oxygen in the water because the surface area of the water is smaller. This will leave very little oxygen for your glofish to breathe.

7. Poor Water Quality

Small-sized fish tanks are usually prone to having problems with water quality. Small tanks make it hard for the nitrogen cycle to work well, which raises the level of ammonia. It will also make your glofish lethargic, lose its appetite, gasp, and have a weak immune system, which is very bad for its health.


Here are some frequently asked questions that people have about how many gallons glofish can be kept in!

How Many Glofish in A 3 Gallon Tank?

A 3 gallon tank isn’t big enough for any glofish. You need at least 2.5 gallons of water for every glofish. And since most glofish need to live in groups, you would need much more than 3 gallons.

How Many Glofish in A 5 Gallon Tank

It’s not recommended to put glofish most glofish in 5 gallon tanks because most types are schooling fish, or require a lot more space. with that being said, you could happily keep a glofish betta in a 5 gallon tank.

How Many Glofish in A 10 Gallon Tank?

Aside from bettas, it’s not recommended to keep other species of glofish in a 10 gallon tank. Glofish sharks are simply too big, and glofish tetras, danios, and barbs need more space to swim.

How Many Glofish in A 20 Gallon Tank?

At 20 gallons, you can comfortable house a school of six glofish tetras, danios, and barbs. As well as this, you can also keep one glofish shark as well as one male glofish betta or 5 glofish bettas.


As you can see, the amount of glofish you can keep per gallon really depends on the type. Glofish bettas do well in 5 gallon tanks, whereas the rest are going to need 20 gallons or bigger to be at their happiest!

If you liked this article, make sure you check out the rest of the website! Otherwise, have a great day!

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