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How Many Glofish Should You Have Per Gallon?

how many glofish per gallon
Who doesn’t want to have the colorful and vibrant GloFish in their aquarium? However, the question that concerns most hobbyists is not knowing the number of GloFish to keep per gallon. Or precisely put, many are afraid of overcrowded conditions. If you are reading this article, that probably means you are also dealing with the same predicament. But don’t worry, we got you.

GloFish is a schooling fish, meaning they must be kept in a group. For a minimum, if you are planning to house 5-6 GloFish, you should get a 20-gallon tank. As it would provide enough space to them and wouldn’t cause stress and suffocation. For a group of 3 GloFish, a 10-gallon tank will do the job.

But it’s not simply about getting a recommendation from the internet for a fixed number of GloFish to keep per gallon and stock them. There is more to it that one must know – such as different varieties of GloFish and how big they can get. Having known all these nitty-gritty will help you determine a proper size aquarium to provide the tiny inhabitants with a thriving environment. So if you have planned to keep GloFish and are serious about the decision, the following sections got it all covered – the things you shouldn’t miss.

GloFish: Understanding the Way of Schooling

If this is the first time you have come across the term “schooling,” there is something you need to know before you get GloFish in your aquarium.

GloFish, as the very name sounds, is a species of fish that is genetically engineered to glow. They are called schooling fish because they prefer to be in a group or school. Schooling is nothing but a typical animal social behavior. Fish mainly adopt such an innate action for protecting themselves from predators. It also improves their foraging and helps them swim more efficiently.

If you lurk around a bit, you will find another term, “shoaling,” being thrown around “schooling.” Both these terms are often used interchangeably, but they are technically different.

In a nutshell, schooling refers to a group of fish swimming in the same direction, at the same speed, and in a coordinated manner. Schools are usually made up of a single species. Whereas shoaling is when a group of fish stays together and swim in a loose group. It can be of different species or the same.

Determining the Number of GloFish Per Gallon

how many glofish per gallon
There is no hard and fast rule about how many GloFish one should have per gallon. It is the same as keeping any other fish.

The only difference with GloFish is that they are schooling fish therefore required to be kept in a group. To the bare minimum, having 5-6 GloFish would make a decent group. Now, to accommodate a group containing that many members, you will require a 20-gallon tank. As you go up in the number of fish, you will need a bigger tank.

If you are a beginner hobbyist, and you want to create an even smaller group, that’s completely fine. Let’s say if it’s 3 GloFish you are getting; for that, a 10-gallon will be sufficient. Understandably, a 5-gallon tank is out of the equation for a social species like GloFish that thrives in a group.

Moreover, these species are highly active and tend to swim together in a group mainly in a coordinated manner, so make sure to have a slightly bigger tank than what is used for usual fishes. Roughly, one GloFish will require a minimum of 3 gallons of water, ensuring comfort and a healthy living environment.

We hope you got the gist as to how you can go about keeping a number of GloFish in a sized aquarium.

How Big Do GloFish Get?

Considering how big a GloFish can get, is also an important factor you must pay attention to when deciding the size of an aquarium.

Mainly, there are 4 popular types of GloFish, namely, Danio, Tiger Barbs, Tetras, Rainbow Sharks. Each has different characteristics and behavior, including the size they can obtain over time.

GloFish Danio: this is one of the most common species of GloFish. Danio remains small in size and grows up to a maximum length of 2.5 inches over their lifetime. They prefer darting a lot and can often be seen chasing tank mates, so it would be favorable to have some extra space.

GloFish Tiger Barbs: quite popular among fishkeeping fanatics, tiger barbs can get around 2.8–3.9 inches long and 1.2–1.6 inches wide in the aquarium. Being semi-aggressive in nature, you must provide them with ample space to swim and not overcrowd the tank. Understandably, they are not easy to get along with other species.

GloFish Tetras: tend to be peace-loving, tetras remain small in size and only reach a maximum of 2.5 inches as a full-size adult.

GloFish Rainbow Sharks: these aren’t actual sharks but belong to the minnow family. They can easily grow up to 4-6 inches in length, and therefore, you should only place them in a 20-gallon tank or larger.

Ideal Conditions for Keeping GloFish

how many glofish per gallon
Although there is nothing special about taking care of GloFish than their non-fluorescent counterparts, there are quite a number of things you must follow.

First of all, like any other fish species, you will be required to maintain optimal water quality with regular water changes and adequate filtration for GloFish. Being a tropical freshwater species – except danios, all GloFish varieties need a constant water temperature at 75-80°F (24-27°C.) If the winter season is approaching, you are going to have a heater installed in your aquarium.

As we know, GloFish need blue light to maintain their fluorescent glow. However, you don’t have to leave the light on for 24 hours. You must turn off the blue light at night because it is believed that darkness promotes good sleep in fish.

Frequently Asked Questions

Q. Can we keep a GloFish alone?

It’s not suggested to keep a GloFish alone in an aquarium as it’s against their innate behavior and will cause stress. You must keep them in a group. Early deaths have been reported in cases where GloFish are not placed in a group.

Q. How many GloFish should be kept together?

GloFish are best kept in groups of at least 6 or more of the same species. Danios and Tetras will be easy to get together. However, it’s not the case with Tiger Barbs, as they come out semi-aggressive and have the tendency to attack other fish.

Q. What is the lifespan of a GloFish?

The lifespan expectancy of GloFish depends on the species, but on average, they live around 3-5 years or more with proper care. There have been many cases of rainbow sharks living up to 11-13 years. So we really believe how you maintain your aquarium quality will significantly affect how long your GloFish live.

Q. What will happen if you overcrowd your aquarium?

It’s a matter of great care to only have a certain number of GloFish depending on the aquarium size. Overcrowding often leads to major stress and diseases in inhabitants. Moreover, it will cause aggression in the fish. It’s always better to have less fish and healthy living space than more fish and poor health.


So it’s time to wrap this detailed guide on GloFish and how many of them to have per gallon. We hope it adequately answers all of your bugging questions around the topic. If you still feel like something is missing on our part, feel free to let us know.