How Many Neon Tetras In A 10-Gallon Tank? With Bettas And Guppies?

Dec 9, 2021

How Many Neon Tetras In A 10-Gallon Tank?

Neon tetras are my favorite species to stock in small to medium-sized tanks. They lend an explosion of bright colors to your tank, produce little waste, and are as hardy as they come. So, if you’re dabbling in the hobby for the first time, neon tetras make an excellent choice. And that takes me to our question of the day: how many neon tetras in a 10-gallon tank? 

I have my own opinion on this matter. But then I also ransacked through Reddit and a dozen forums (not exaggerating), where I came across a few interesting answers and findings. 

So, I’ll tell you about it all in this blog. 

Let’s roll! 

How Many Neon Tetras In A 10-Gallon Tank?

Neon tetras are schooling fish. If you keep several of them in a small tank, they will just hoover at one spot. So, we’d recommend not adding any more than 6 neon tetras in a 10-gallon tank. If you really know your way around ‘overstocking,’ you can get away with keeping 7-8.

But we’d still strongly recommend sticking to 6 for a 10-gallon tank. 

However, note that your neons most likely won’t school in a tank that small. Instead, they’ll just hover at one spot. So, your tank wouldn’t look as exciting as you’d want it to. 

If you are looking forward to observing their unique schooling behavior, you might want to get a bigger tank! 

There are many different methods and formulas to calculate the stocking number for any given tank size. 

There’s this popular yet debatable “one inch per gallon rule.”

Then there’s a more liberal “one inch per two gallons” rule.

And the last one, given by a veteran aquarist and used by big shots in the hobby, is “12 square inches of surface space for each inch of the tropical fish”.

So, what formula should we use to find out how many neon tetras in a 10-gallon tank?

Let’s have a look! 

Calculating Neon Tetras Stocking Number For A 10-Gallon Tank

One Inch Per Gallon Rule 

The “one inch per gallon” formula is not applicable for all fish. Imagine adding a 10-inch oscar fish in a 10-gallon tank.

However, we can use this rule for small fish under 3 inches without any issue. 

Most neon tetras grow around 1.5 inches long. But to stay on the safe side, let’s assume the average size of the tetra to be 1.75 inches, okay?

So, let’s divide the gallon capacity by the tetra’s size. 

= 10/1.75

= 5.7 

So, you can fit 5.7 neon tetras in a 10-gallon tank. But you can round it off to 6. 

Therefore, when following the “one inch per gallon” rule, you can safely stock 6 neon tetras in a 10-gallon tank. 

12 Square Inches Of Open Tank Surface For An Inch Of Fish Rule

This rule was given by veteran aquarist and author Dick Mills in his book You And Your Aquarium. According to him, we should allocate at least 12 inches of open tank surface for every inch of the fish’s body for tropical fish like tetras. 

So, let’s begin the calculations!

A standard 10-gallon tank has the following dimensions: 

= 16 x 8 x 10 inches (L x W x H)

Surface area of a 10-gallon tank = L x W

= 16 x 8 = 128

Total inches of neon tetras a 10-gallon tank can hold = Surface area/12

= 128/12 

= 10.6 inches 

Now, let’s assume the average height of a neon tetra is 1.75 inches. 

So, total number of neon tetras a 10 gallon tank can hold = 10/ 1.75

= 5.71

Let’s round it off to 6.

So, according to this rule, the maximum number of neon tetras a 10-gallon tank could hold is 6 as well. 

Okay, enough maths for today. Now, let’s look at what real hobbyists have to say on the matter. 

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How Many Neon Tetras In A 10-Gallon Tank? Public Poll 

I rootled around several forums to look for what hobbyists had to say on the matter. This is my small attempt to give you unbiased, neutral, and inclusive opinions to make an informed decision. 

All the opinions expressed below purely belong to the respective authors. 

“I think I would get around 6-8. That would be fine, assuming that you keep up on the maintenance and water changes. However, most fish won’t school in that size of a tank. It’s not just big enough.”

“I would get about 6 or so and a few (2-3) ghost shrimps for the bottom. As long as you keep up with maintenance, you should be okay. Just don’t forget to read up on cycling. If you drop 6 on day 1, you will end up with 6 dead fish on day 3.”

“I’d say 6-8 should work. Then maybe bump to 10 if things are staying stable.”

“Neons would be okay in a 10-gallon tank bioload-wise. But from my observation, they are quite boring to look at in small tanks. They’ll just hoover at one spot.”

“No, no, no. You cannot stock 3 to 4 neons per gallon. You can stock one per gallon.”

How Many Neon Tetras And Guppies In A 10-Gallon Tank? 

Neon tetras and guppy
Credits: Kai Mun Lee (Creative Commons license)

If you’re going to add 2 guppies in the tank, you can comfortably add 3 neon tetras to accompany them. Similarly, if you are going to add 3 guppies, you can add just 2-3 neon tetras. 

I’ll tell you how we did the calculations. 

Guppies make wonderful tankmates for neon tetras. They’re sociable, easy to care for, and absolutely pretty. But they grow a little bigger than neon tetras. 

Males can grow as big as 1.5 inches (1 inch on average), while some females are known to reach 2.4 inches long (2 inches on average). 

Let’s assume the guppies’ average length to be 2 inches for this calculation. 

So, once again, going by the “one gallon per inch” rule, we can add (10/2 = 5) 5 guppies in a 10-gallon tank. 

But we’re here to calculate how many guppies and neon tetras can together go into a 10-gallon tank. 

For the sake of this example, let’s assume that we have allocated 4 out of 10 gallons for the guppies. So, you can add 2 guppies (4/2 = 2).

Now, for tetras, we have 6 gallons left. So, we can add (6/1.75 = 3.4) around 3.4 tetras in a 10-gallon tank. 

Let’s round it off to 3. 

How Many Neon Tetras And Bettas In A 10-Gallon Tank?

Credits: maxxum (Creative Commons license)

Using the same calculation method as above, you can keep precisely 1 betta with 2 neon tetras. 

Once again, let’s see how the calculations are done. 

Betta grows up to 2.5 inches long on average. And although the rule of thumb is 3 gallons for each betta, we’d recommend at least 5 gallons. 

So, assuming that your betta fish needs 5 gallons, you have a total of 5 gallons left for tetras. 

You know the drill. Now, let’s divide 5 by 1.75. It gives us 2.8. 

Now, you can round off 2.8 to 3. 

So, you can fit 1 betta with around 3 neon tetras. 

However, I’d suggest you not house bettas and tetras together in a tank as small as 10 gallons. 

Bettas are inherently territorial. They need ample space to feel comfortable and happy. If they were to be housed in a 10-gallon tank with other species, it’d only fuel their stress and aggression. 

And on top of that, neon tetras are fin-nippers. They will definitely go after your betta’s long, flowy fins.

The Downsides Of Keeping Neon Tetras In A Small Tank 

I know it’s not always possible for us to commit to a big tank. But it’s important to know that managing a small tank exactly isn’t a walk in the park. Some downsides of a small tank are lack of schooling behavior, the stress in fish, volatile water parameters, and possibly stunted growth. 

You Cannot Observe Schooling Behavior 

You need to keep at least 10-15 neon tetras together for them to school. In a small 10-gallon tank, they will simply hover over one particular spot. 

Frankly, this is going to look boring. 

So, you will definitely miss out on observing this fascinating schooling behavior. In my opinion, a 20-gallon tank would be a better fit. 

It’s Impossible To Raise A Community 

You already know that you will have extremely limited options of fish or other creatures to add to a 10-gallon tank. As you can tell from the calculation above, you can only keep 1 betta with 2-3 neon tetras. 

So, if you’re looking forward to creating a unique community and ecosystem in the tank, this is simply not possible in a 10-gallon tank unless you prefer overstocking. 

Small Tank Can Stunt Fish’s Growth

Several studies have shown that fish release a certain chemical/pheromone into the water that can hinder the growth of other fish of the same species. 

This is not a concern in a big water body like a sea or a lake. These pheromones will get washed or swept away in an instant. 

However, these chemicals have nowhere to go in a closed system like an aquarium. So, naturally, they will get absorbed into the fish’s body, which can potentially stunt their growth. 

Your Neon Tetras Will Stress 

Like all fish, neon tetras will get scared and stressed over the slightest hitch. But we cannot really blame them. They’re hardwired to feel the way they do. 

Factors like a cramped tank, dirty water, bullies, and lack of resources will severely stress a fish. So, the brain will stir up hormones to get through the stress as a response. 

In the wild, they can swiftly get away from the stress-inducing factor. And naturally, the hormones will reset to normal.

However, in the tank, the fish will go on stressing until you take notice and do something about it. 

So, by the time you do anything about it, the fish will experience a plethora of symptoms like lack of appetite, lowered metabolism, suppressed immunity, and stunted growth. 

Tank Maintenance Will Keep You On Your Toes 

As beginners, we often assume that a small fish tank is easier to look after. And while I wouldn’t say the opposite is true, it’s definitely not a piece of cake to care for a small tank. 

That’s because the water parameters are volatile in a small enclosure, and they change quite abruptly. You will end up constantly monitoring the fish’s environment and perform water changes more frequently. 

Put simply, a small tank offers less room for mistakes. 

Frequently Asked Questions 

Credits: Geek2Nurse (Creative Commons license)

How Many Neon Tetras In A 3-Gallon Tank?

A 3-gallon tank would hold 3 neon tetras. I wouldn’t advise adding more than that, as the fish will lead an impoverished life. 

How Many Neon Tetras In A 5-Gallon Tank?

A 5-gallon tank will hold 3-4 neon tetras. Therefore, you won’t really be able to observe their schooling behavior. 

How Many Neon Tetras In A 7-Gallon Tank?

A 7-gallon tank can hold 4-5 neon tetras. Once again, you won’t school in such small numbers. 

How Many Neon Tetras In A 15- Gallon Tank?

A 15-gallon tank will hold 10 neon tetras at max. They will even school around in your tank. 

How Many Neon Tetras In A 20-Gallon Tank?

A 20-gallon tank will hold around 12-13 neon tetras. 

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

You can add around 6 neon tetras in a 10-gallon tank. You can follow the “one inch per gallon rule” for small fish like tetras that won’t grow over 3 inches. However, don’t apply this technique to big fish. 

Note that tetras won’t most likely school in a 10-gallon tank. So, if you’re looking forward to their iconic schooling behavior, you might want to upgrade to a bigger tank and stock some more tetras. 

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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.