How Many Glofish Danios In A 10-Gallon Tank? 5 Or None?

Jan 2, 2022

How Many Glofish Danios In A 10-Gallon Tank?

Image Credit: Ho-Wen Chen (Creative Commons license)

The official glofish website recommends adding at least five glofish danios to your aquarium. That sounds about right ✔️. It then says you can ‘safely’ add 2 danios per gallon of tank space. Incorrect ❌! 

By that logic, you can add 20 glofish danios in a 10-gallon tank! But my dear friend, that’s just some wishful thinking. 

I was horrified to know the extent of misinformation littered on their site! It’s really unfortunate that they have touted glofish as low-maintenance fish suited for teeny tiny tanks. 

So, here I am – trying to fight dishonesty and fabrication one article at a time. In this edition, we will discuss the number of glofish that can go inside a 10-gallon tank. 

Let’s begin without further ado! 

How Many Glofish Danios In A 10-Gallon Tank?

Technically, you can fit 4-5 glofish danios in a 10-gallon tank if you were to follow the ‘one inch per gallon’ rule. However, danios are schooling fish that need to be ideally kept in groups of 6 or more. On top of that, they’re highly active and need ample space to dart around. A 10-gallon tank simply doesn’t have enough room to accommodate their needs. 

As I said above, you can house around 4-5 of these fish if you were to follow the controversial ‘one inch per gallon’ rule. 

To be more specific, a glofish danio grows about 1.8 inches (4.5 cm) long. But it’s always safer to overestimate the size. So, let’s suppose they grow around 2 inches (5 cm) long. 

So, calculations say you can add 5 glofish danios in a 10-gallon tank. And 5 is just 1 number short of 6. So, what difference does it make? Sounds tempting, right?

Here’s why this rule is dangerous. It doesn’t consider the space taken by the substrate and decor, the waste produced, fish’s height, and the need for schooling. 

I know the general consensus is that this rule can be safely applied for fish under 3 inches. But I’d still recommend against it because glofish are schooling and super active fish. 

Below, I’ll lay down a few reasons why glofish danios aren’t suited for a 10-gallon tank.

Don’t get disheartened, please!

Recommended Readings!

How Many Glofish Danios In A 5-Gallon Tank? You Might Not Like My Answer!

How Many Glofish In A 3-Gallon Tank? Zero!

How Many Glofish In A 20-Gallon Tank? Honest Answers!

How Many Glofish In A 10-Gallon Tank? Zero?

Why Shouldn’t You Keep Glofish Danios In A 10-Gallon Tank?

The main reason glofish danios are not suited for a 10-gallon tank is that they’re schooling fish that find safety in numbers. A 10-gallon tank’s dimensions are 20″ L x 10″ W x 12″ H. And that’s simply not enough space for an active school of these fish to thrive in. They need a tank bigger – and especially longer – than that. 

Glofish Danios Are Schooling Fish

Glofish danios are hardwired to school. They have evolved over millions years to swim in schools to protect themselves from predators, enhance their foraging skills, and swim more efficiently. 

And mind you, unlike shoaling, in which fish simply swim loosely together, schooling demands more coordinated body positions and synchronized movements. 

So, when you deprive a fish of its innate instinct to swim, the fish will become depressed and irritated. Really – I’m not dramatizing stuff here. 

Lack of schooling can make fish severely stressed. And apparently, stress hinders white blood cells production, weakening the fish’s immunity and making it susceptible to dozens of pathogens ubiquitous in all tanks and waiting for the right moment to strike. 

That’s not all.

When unable to school, glofish danios will become cross and lash out at each other. They will chase each other around and nip fins. 

Glofish Danios Are Active And Sporty

Anyone who’s raised danios will tell you that they’re crazy active. And it’s the same for glofish danios. These fish absolutely love to dart around the tank. They will constantly pace left and right like a flash. 

And as you can guess, a 10-gallon tank doesn’t provide enough space to satiate their ‘athletic’ demands. 

As a result, your glofish danios will become bored out of their brains. And it doesn’t take much for a bored fish to turn angry. 

Without anywhere to ‘go’ and anything to do, your glofish danios can become irritable. 

Ideally, these fish need a long tank to do all those laps. Active swimmers need that distance. Plus, it will be really amusing for you to watch them dash through the tank. 

Small Tanks Are Difficult To Keep

It’s far too common for advertisers to pitch small tanks as ‘beginner-friendly’ and even ‘self-maintenance.’ But that’s as deceptive and, dare I say, fraudulent as they can get. 

Small tanks are in no way – absolutely no way – easy to look after. As a matter of fact, these tanks are super volatile and prone to accidents. 

Heed my advice – beginners should absolutely stay away from small tanks. Even the most minor fluctuation in one part of the tank can be felt through the entire tank in no time. 

There would be no time to make amends. 

Likewise, honest mistakes and sometimes things out of your control can lead to two very different consequences in a small and big tank. 

For example, a certain spike of ammonia in a small tank can make the entire environment toxic and inhospitable, while it may not be much of a concern in a big tank since it can get diluted easily and cause less harm. 

Small Tanks Can Stunt Fish’s Growth 

There’s a common belief that fish grow to the size of their tank. While there’s no scientific backing to prove this, it’s certainly true that small tanks can stunt a fish’s growth. 

Let me explain how. 

Glofish danios are active fish, to begin with. I know I’ve said it like 10 times before, but they really are. They need a sizable space to swim and play around. 

If they don’t get the exercise they require, it can very well negatively impact their growth. It’s not farfetched to assume that they won’t grow to their full-size potential. 

Similarly, fish tend to get stressed in congested environments. The water will be relatively more polluted, there will be animosity surrounding the territory, and there won’t be enough room to swim around. 

And as I said above, stressed fish will have compromised immunity. They will fall sick more often. So naturally, an unhealthy fish will not grow healthily. 

Lastly, studies have pointed out that fish release pheromones into the water that can stunt the growth of other fish of the same species. This can really be a problem in a closed system like an aquarium. 

There’s still a lot to be discovered on the subject, and it may not be true for all fish, but it’d be wise to consider things from this angle as well. 

Small Tanks Can Shorten Fish’s Lifespan 

Increased stress, lack of exercise, stunted growth, and toxic water – these reasons are more than enough to effectively kill your fish at a young age. 

As evident from the points mentioned above, it’s clear that small tanks force fish to lead impoverished and unhappy life. It’s even truer for fish like sporty and social fish like glofish danios. 

Therefore, consider getting a bigger tank if you really want your fish to have a good time. It’s easier on you too. 

It’s a lot more forgiving. You won’t have to constantly be on your toes to maintain the ever-changing water parameters. 

Now, let’s look at what real hobbyists say about keeping glofish danios in a 10-gallon tank. 

How Many Glofish Danios In A 10-Gallon Tank? Real Answers By Real People! 

This newly-added segment is my attempt to give you honest and well-rounded information so you can make informed decisions for your fish. 

Note: All the opinions expressed purely belong to the respective owners!

Credits: Ho-Wen Chen (Creative Commons license)

“I would purchase a 20-gallon tank instead of a 10-gallon one, if you haven’t already bought it. Bigger tanks are easier to manage than small ones.”

“Danios can get up to 2.25 inches long. Plus, they’re quite active. I wouldn’t keep my danios in anything as small as a 10-gallon tank.”

“I would strongly discourage keeping glofish danios in a 10-gallon tank. They are speedy swimmers that need a ton of space. They also pick on each other.”

“Danios are way too active for a 10-gallon tank. I have 3 in my 20-gallon tank, but even they move around a lot.”

“I would suggest a 20-gallon long or 30-gallon long for these fish as they require horizontal space and not vertical. A standard 20-gallon tank is only taller than a 10-gallon tank. So go for a long one that gives more horizontal space.”

“My danios are wild. They love to fly around the tank like speed demons. Fun to watch, but they really do need some swimming space.”

“The thing about glofish danios is that they like to swim a lot – so, the longer the tank, the better. A 20-gallon tank comes in 3-different sizes – tall, extra tall, and long.”

As you can see from the quotes above, most hobbyists recommend against keeping glofish danios in a 10-gallon tank. 

However, one person had a different opinion. He said he was able to successfully keep a few of them in a 10-gallon tank. 

Have a look at what he had to say. 

“I have 5 glofish danios in a 10-gallon tank, and they get along splendidly. All these talks about them being too fast – do you think they will ram into the glass? My fish have plenty of room to swim and turn around. 

As long as there aren’t any obstructions blocking the top part of the tank, they can do those laps with pleasure.”

Hmm.. something to think about! 

Frequently Asked Questions

Credit: Ho-Wen Chen (Creative Commons license)

How Many Glofish Danios In A 5-Gallon Tank?

Technically speaking, you can keep 2 glofish danios in a 5-gallon tank

But since they’re schooling fish, they need to be in a big group. Moreover, they’re pretty active and playful than your average fish. So, it’s not really a good idea to keep them in a 5-gallon tank. 

How Many Glofish Danios In A 20-Gallon Tank?

You can keep around 10-12 glofish danios in a 20-gallon tank. But remember, it should be a 20-gallon long tank. 

The standard 20-gallon tank is only taller than a 10-gallon tank. 

How Many Glofish Danios In A 30-Gallon Tank?

You can keep around 14-15 glofish danios in a 30-gallon tank

This would be the perfect number to watch them school and their other unique antics. 

How Many Glofish Danios In A 40-Gallon Tank?

You can add around 20 glofish danios in a 40-gallon tank

But if you’re a beginner, I’d recommend understocking at first. Then, you can gradually increase the number once you gain enough confidence. 

Final Words: How Many Glofish In A 10-Gallon Tank?

Even though you can fit 4-5 glofish danios in a 10-gallon tank, I suggest getting something bigger. Upgrade to a 20-gallon long tank. It’ll make life easier for both parties.

Glofish danios, like their original counterparts zebra danios, are as playful and active as they come. They just love to dart and pace around the tank all day, every day. A 10-gallon tank can’t provide enough room for all that. 

Plus, they’re schooling fish. Ideally, you should keep at least 6 of them together. A 10-gallon tank wouldn’t fit that many. 

Recommended Readings!

How Big Do Glofish Tetras Get? Grow Them Fast!

What Do Glofish Eggs Look Like? Photos And Videos!

How Long Can Glofish Go Without Food? Which Species Can Go The Longest?

rohit gurung author at urbanfishkeeping

About Rohit Gurung

My never-ending love and fascination with Aquascaping started when I received a red-eared turtle for my 10th birthday.

Apart from researching and writing, I spend hours gazing at my 3 turtles. And yeah, I bask alongside them too.