Skip to Content

How Many Neon Tetras In A 5-Gallon Tank? Honest Answers!

How Many Neon Tetras In A 5-Gallon Tank? Honest Answers!

Neon tetras are beginner-friendly fish. They’re simply stunning to look at, move in schools, produce tiny bioload, and are pretty hardy. So, I’d definitely recommend them if you’re a beginner starting with a modest tank! But what tank size is too small for these fish? For instance, how many neon tetras in a 5-gallon tank? 

Is it even possible? Let’s find out! 

How Many Neon Tetras In A 5-Gallon Tank?

For small fish like neon tetras, we can follow the “one inch per gallon” rule. So, my calculations say that you can add 3 neon tetras in a 5-gallon tank. However, I’d recommend against it. Tetras are schooling fish that at least need to be in a group of 6 to be comfortable. 

Calculate Stocking Number For Neon Tetras 

The “one inch per gallon” rule is debatable. While some swear by it, others call it bogus in its finest form. The main caveat of this rule is that it doesn’t take the fish’s height or the space taken by decors and plants into account. 

However, this rule is still acceptable for fish as small as neon tetras. 

So, most neon tetras grow only around 1.5 inches (4 cm) on average.

But for calculations, let’s assume the fish grows about 1.75 inches long to give some room for mistakes. 

Let’s divide the gallon capacity by the fish’s size. 

= 5 / 1.75

= 2.8

So, a 5-gallon tank can house exactly 2.8 neon tetras. So, of course, we will round it off to 3. 

Therefore, the final answer is 3. 

Although the calculations show that you can house 3 neon tetras in a 5-gallon tank, if I were to give you my opinion, I’d say you could house exactly 0. 

Don’t get me wrong. I’ll tell you why.


Why Should You Not House Neon Tetras In A 5-Gallon Tank? 

cardinal tetra

Neon tetras are schooling fish. They’d only feel comfortable in a group of at least 6-10. Also, they’re active swimmers. A 3-gallon tank is simply not big enough for them to feel comfortable in. 

Plus, there are at least half a dozen drawbacks small tanks can potentially invite. Let me go through them briefly. 

Your Neon Tetras Won’t School 

Tetras love to school. And they don’t do it just to flaunt coordinated body positions and synchronized movements. Instead, they do so to protect themselves from predators, improve foraging skills, and swim more efficiently.

Schooling is an inherent basic instinct for tetras, and we aren’t entitled to deprive them of it. It would be best if you kept neon tetras at least in a group of 6-10 in a 20-gallon tank for them to be able to school. 

When they can’t move in groups, they get stressed. And I’ll tell you exactly what happens when neon tetras are stressed. 

Your Neon Tetras Will Be Stressed

Although tetras make one hardy species, they’re prone to stress at the slightest inconvenience like any other fish. And the chances of stress amplify in a small tank. 

The reasons could range from polluted water and lack of space to volatile temperatures and lack of hiding places. 

And when stressed, a fish’s brain stirs up certain hormones to help the fish relieve. Also, your neon tetra can quickly swim away from the stress-causing factor in the wild. And consequently, the hormones will reset back to normal. 

But in an enclosed system like a 5-gallon tank, the fish cannot get away from the trouble. It will keep on stressing, and the hormonal imbalance will be persistent unless you notice and do something about it. 

And by the time you intervene, the fish will experience a plethora of repercussions like compromised immunity, lowered metabolism, lack of appetite, and stunted growth.

As you already know, these reasons – single-handedly or collectively – are more than capable to stress your fish.

Growth Can Be Stunted 

Research has shown that fish release pheromones in the water that can inhibit the growth of other fish from their own species.

Now, this is not much of a concern in a big water body like a river or sea. These chemicals will get diluted and washed away without a trace. 

But in a closed system as small as a 5-gallon tank, these pheromones have nowhere to go. So they will keep on moving in circles until they get absorbed into the fish’s body. 

So, if you’re keen on growing your tiny tetras to the maximum possible size, you might want to switch to a bigger tank. 

Water Will Get Dirty Quickly 

Even though neon tetras produce considerably less waste, the toxic buildup will happen a lot quicker given the tank’s small size. 

The tank will be very much prone to spikes of harmful compounds like ammonia, nitrite, and nitrate. And even the slightest increase in their concentration can prove fatal if you don’t intervene at the right time. 

Also, the water parameters will be a lot more volatile in a small tank. For instance, even the slightest temperature change can be felt through the whole aquarium instantly. 

Therefore, you need to be on your toes all the time. 

Recommended Articles!

How Many Tetras In A 3-Gallon Tank? Will Small Tank Stunt Growth?

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

How To Keep Neon Tetras In A 5-Gallon Tank? 

neon tetra

If you are absolutely bent over backward to keep neon tetras in a 5-gallon tank, there are a couple of things you can do. Here, the main key to success is aquascaping. The tank must have at least two objects rising into the mid-levels at 2 or more places. This will provide the fish with a sense of security and amusement. 

Plants are your best bets, but driftwoods work pretty well too. 

Below, we will discuss the things you need to do to ensure the wellbeing of your neon tetras in a 5-gallon tank. 

Don’t Skip Water Changes 

There’s no one rule set in stone. The answer for how much and when to change the water will vary from one hobbyist to another. 

For a 5-gallon tank with around 3 neon tetras, I would suggest changing about 25-30% water every week. 

As I said above, the water will get polluted quickly in a small tank. Therefore, you need to stay on top of them. 

But don’t go overboard and overkill it. Changing water more often and in more percentage than needed will swiftly eliminate the tank’s good bacteria colony and backfire in the most unpleasant ways.

Don’t Add Too Many Decors 

Sorry for stating the obvious, but a 5-gallon tank is pretty small, to begin with. There’s not enough space for fish to swim around freely, let alone add decorations. 

So, don’t go overboard with adding too many decors or plants to enhance the tank’s aesthetics. 

I’d suggest adding one or two cave-like rocks for the fish to retreat in when stressed and two plants rising into the mid-levels. 

You don’t want to meddle with neon tetras’ swimming regions. They’re pretty active swimmers and would prefer open spaces. 

Get Reliable Equipment 

Yes, a 5-gallon fish tank still needs a filter, heater, and air pump. I cannot stress this enough! 

With 5-gallon tanks, proper filtration is an indispensable part of the equation. That’s because waste and impurities will build up a lot quicker in a small fish tank. 

Likewise, a reliable heater is essential to maintain the water temperature between 72-76 degrees Fahrenheit ( 22-24 degrees Celsius). 

And finally, you will also need to get an air pump with an output of at least 0.165 liters per minute. 

Since small tanks are susceptible to abrupt changes in parameters, you mustn’t skimp on equipment. 

Don’t Add Other Fish 

A 5-gallon tank won’t have enough space to house any more than 3 tetras. Therefore, adding any other fish or crustaceans is out of the question. 

Neon tetras aren’t known for their aggression. However, they can get pretty mean and territorial if they feel stressed or uncomfortable. 

When anxious, they’ll resort to what they do the best – nip fins. So, I don’t recommend adding any other fish to a 5-gallon neon tetra tank. 

Below, I have garnered a few answers from hobbyists on different forums on the subject. This is my attempt to help you make an informed decision without having to scour through a dozen forums. 

How Many Neon Tetras In A 5-Gallon Tank? Real Answers By Real People! 

Note: The quotes listed below purely belong to the respective authors. 

glofish tetra

“Neon tetras are social, schooling fish that need to be kept at in a group of 6 or more. They should be kept in a minimum of a 10-gallon tank. Only 3 fish equals constantly stressed out fish and heightened chances of diseases like ich.”

“Neon tetras expect to have a more horizontal swimming room than what a 5-gallon tank provides. As a matter of fact, you really should expand the tank to at least 10 gallons. Even better would be a 20-gallon tank.”

“I would never have less than 5 neon tetras in a display tank. They crave to be in a school, and their beauty lies in their schooling.”

“I don’t believe neon tetras are suitable for a 5-gallon tank. A 10-gallon tank is considered a minimum, but a 20-gallon tank will bring out the best in them. I’d also recommend a school of 8+.”

“I would not try to keep neons in a 5-gallon tank. A slower-moving species would be more appropriate.”

All the quotes by different authors tell that it’s really not advisable to keep neon tetras in a 5-gallon tank.

However, don’t feel disheartened. There are a few hobbyists – really few – that have had pleasant experiences. 

Here’s what he has to say:

“I had kept 3 neon tetras in a 1.5-gallon tank for 6 months. Then I upgraded to a 3-gallon tank with a snail, 2 more neons, and an albino suckerfish. They’re all happy. The neons even lay eggs sometimes, which I remove. I’ve also added 2 decors for them to hide in when needed and a moss ball to keep the water regulated. I use a simple whisper filter and an LED light. So, I have a successfully thriving 3-gallon tank with 5 tetras, a suckerfish, and a snail. Everyone says that breaks the ‘one inch per one gallon’ rule, but each fish is different, and the rule doesn’t always apply. But note that I take EXCEPTIONALLY good care of my tank.”

I have included quotes both in support of and against adding neon tetras in a 5-gallon tank. As I said above, I just want you to make an informed decision.

Like you can see, although it’s not really recommended, it’s not entirely impossible if you know your way around small tanks. 

Frequently Asked Questions 

How Many Neon Tetras In A 5-Gallon Tank With Betta?

Bettas and neon tetras cannot cohabitate in a small 5-gallon tank. Bettas at least need 5-10 gallons for single fish to feel comfortable. 

On top of that, bettas are highly territorial. And your neon tetras will have a good time nipping the betta’s long, flowy fins. 

So, unfortunately, it’s not possible. 

How Much Does A 5-Gallon Fish Tank Weigh? 

An empty 5-gallon fish tank weighs around 7 lbs, while the weight will increase to 62 lbs when filled with water. That’s an increment of almost 9 times. 

How Big Is A 5-Gallon Fish Tank?

A 5-gallon fish tank’s measurement is 16″ x 8″ x 10″ (L x W x H)

If you’re interested to read up on the weight and dimensions of tanks ranging from 2 and a half gallons to all the way up to 225 gallons, check out this article

Final Words: How Many Neon Tetras In A 5-Gallon Tank?

You can only add around 3 neon tetras in a 5-gallon tank. 

But these fish need to be kept in a group of 6 to feel comfortable and be able to school. And a 5-gallon tank is nowhere big enough for that. 

Therefore, we recommend keeping them in a 20-gallon tank if you want to observe their unique schooling behavior. 

However, if a 5-gallon tank is all you can provide right now, don’t forget to keep a watchful eye on the water parameters. Even the most minor fluctuation can invite catastrophic damage in small tanks. 

Recommended Articles!

How Many Angelfish In A 40-Gallon Tank? Will They School?

How Many Angelfish In A 29-Gallon Tank? Do They Shrink In Small Tank?

How Many Angelfish In A 75-Gallon Tank? Use This Golden Rule!

How Many Angelfish In A 55-Gallon Tank? Use This Formula!

How Many Cichlids In A 75-Gallon Tank? Mbunas, Peacocks And South American

How Many Cichlids in a 55-Gallon Tank? Use This Simple Formula!

How Many Cichlids In A 40-Gallon Tank? Cichlid List For A 40-Gallon Tank