A well-stocked neon tetra can be a masterpiece of art. It is a conversation starter. It’s a spectacular sight to see the combination of geometric schools and a burst of red and blue colors. If you are just starting out in the hobby, a 20-gallon tank of neon tetras can be a great place to start. The question is: How many neon tetras can you fit in a 20-gallon tank for neon tetras?

How Many Neon Tetras In A 20-Gallon Tank?

In a 20-gallon tank, you can add anywhere from 10 to 30 neon Tetras. This is a huge range. But let me tell you. 10 is a good starting point. If you are an experienced fishkeeper and confident with overstocking, 30, is possible.

Many hobbyists have kept and recommended keeping at least 30 neon tetras within a 20-gallon aquarium. This is what I’ve found.

Keep in mind that stocking numbers are affected by the tank you have. A 20-gallon tank with a longer footprint can raise more neons than a 20 gallon tank with a larger capacity.

Hobbyists use a few rules to determine the stocking amount. There are two options: the controversial “one-inch per gallon” rule or the more liberal “12 sq inches of surface area per inch of the body”.

Let’s now see how stocking numbers would look if we followed these guidelines.

The 1 Inch per Gallon Rule

This rule, as I mentioned above is highly contested. This is because it doesn’t take into account the space taken up by decorations, plants, or substrate. During calculation, it completely disregards the fish’s size.

This rule is only applicable to fish less than 3 inches in length. It is completely absurd for larger fish. Imagine adding a 12-inch oscar in a 12-gallon tank.

Neon tetras average 1.5 inches (4 cm in) in length. Let’s say they measure 1.75 inches (4.45 cm) in length.

A 20-gallon tank would hold 11.42 (20/1.75) neon Tetras. Or, you can round it up to 11 or 12.

The 12 Square Inches For Every Inch Rule

Dick Mills, a renowned fishkeeper and author, gave this rule in his book You And Your Aquarium. This rule is also a favorite of many fish hobbyists.

According to them, the tank’s surface and floor area should be considered when calculating the stocking amount. This is because oxygen exchange takes place at the top and good bacteria processes fish waste at base.

In 3 easy steps, I will show you how to calculate stocking numbers based on this rule.

Step 1

Calculate the surface area by multiplying the tank’s length and width (LxW)

Step 2

Divide the tank’s surface area by 12 to calculate the maximum number of fish it can hold (surface area /12).

Step 3

Divide the result from step 2 by the fish’s height to calculate the total fish tank capacity. (Total inches of fish that the tank can hold/fish’s length).

Let’s now calculate the stocking quantities for a 20 gallon tank that is high and a long tank that is 20 gallon in length.

A 20-gallon tank can be purchased here

Dimensions of the tank: 24″x12″x16″ (LxWxH).

To be safe, let’s assume that the neon tetras measure 1-inches tall. According to what I’ve read, the average height of neon tetras is just 9-12mm (0.35-0.47) inches.

Let’s first calculate the surface area of the tank.

L x W = 24″x12″ = 288

Let’s now find out how many neon tetras can be stored in a 20-gallon tank.

Surface area/12 = 288/12 = 24,

Let’s finally calculate how many neon tetras can be housed in a 20-gallon tank.

The total tank capacity / the average tank height = 24/1 = 24

We can therefore house approximately 24 neon tetras in 20-gallon tanks if we adhere to the rule of 12 square inches per inch of the fish’s body.

Let’s now calculate the volume of a 20-gallon tank.

20-gallon tank’s long tank’s dimensions: 30” x 12” x 12” (L x W x H)

Surface area = LxW = 30″x12″ = 360

A 20-gallon tank can hold 30 fish in total

The total number of neon Tetras that a 20-gallon tank can hold = 30/1 (fish’s assumed size = 30).

A 20-gallon tank with a long neck can store about 30 neon Tetras.

The answer will depend on many factors, including how frequently you are willing to do water changes, how many decors and plants you have, and your experience with fishkeeping.

Let’s stop with the math. Let’s take a look at what hobbyists actually have to say.

Here are some responses from hobbyists who shared their thoughts on the topic on various platforms. These answers will hopefully help you make an informed and practical decision.

Let’s take a look!

How Many Neon Tetras In A 20-Gallon Tank? Real Answers By Real People!

“I think 20-30 would be fine, depending on the filtration system and your maintenance schedule.”

“30-40 neon tetras wouldn’t be out of question – especially in a 20 gallon long tank – as long as proper filtration is used, water changes are performed weekly, and cleanliness is maintained.”

It all comes down to your ability and willingness to put in the effort to raise X amount of tetras. There are two options: go easy with just a dozen, or go big with 40. However, this will require a lot of work (water changes, filter cleaning, and so on). It would be beautiful to see 40 neons in one tank, but it would require a lot of work strong>

“Will the tank ever be planted?” The bioload of neon tetras is very low. If your tank is very heavily planted strong>, 30-40 will suffice in a 20-gallon container.

“I would recommend keeping around 17. It’s a strange number, but it would make the school look better. It worked great. I was able to get around 20. You should make sure they are from a trusted source so that you don’t end with 20 dead fish in the next day strong>

If you are willing to work hard, it is possible to house 20-30 plants in a 20-gallon aquarium. If you are just starting out in this hobby, and have little experience or confidence, then it is best to limit yourself to 12 plants.

How Many Neon Tetras In A 20-Gallon Tank With Betta?

People often keep bettas within tanks of less than 3 gallons. These fish need to be kept in at least a 5-gallon tank to ensure they live comfortably.

Let’s say the betta requires 5 gallons. The neon tetras will then need 15 gallons. If we use the “one inch per gallon” rule, we can house approximately 8.57 (15/1.75) neon Tetras.

It can be rounded up to 9.

In a 20-gallon tank, you could house approximately 1 betta and 9 neon Tetras. You could house 6 neon tetras if you had 2 bettas.

It is important to understand that neon tetras and bettas are not the best fish to keep in a 20 gallon tank. Because bettas can be territorial and aggressive fish. They require plenty of space in order to feel at home.

Neon tetras can also respond to aggression from bettas by biting their long, beautiful fins. Neon tetras are known for their ability to nip fins.

You can keep them all together as long as they have enough space to swim and claim their own territory.

How Many Neon Tetras And Guppies In A 20-Gallon Tank?

Male guppies can grow up to 1.5 inches (1 in) on average. Male guppies can reach 1.5 inches (1 inch) on average, while females can reach 2.4 inches (2 1/2 inches).

To make things easier, let’s say that the average length of a fish is 2 inches.

If you have 10 gallons of guppies you can keep 5 (10/2) in a 20-gallon storage tank.

You now have 10 gallons left for the neon Tetras. In a 20-gallon tank, you can store 5.7 (10/1.75) neon Tetras. It can be increased to 6.

You can keep 5 guppies or 6 neon tetras inside a 20-gallon tank with 10 gallons each.

How Many Neon Tetras Should You Keep For Them To School?

Neon Tetras are schooling fish which move in large numbers in the wild. If you wish to observe their unique schooling behaviors, keep them in at least 6 fish tanks.

Why Do Neon Tetras School?

Neon tetras are naturally inclined to schooling. This is their primary purpose to defend themselves against their enemies. Predators find it easier to pursue and eat a fish that is swimming alone than to try to cut off a large group of fish.

This helps the tetras protect their territory. It’s no surprise that the bullies are hesitant to confront a school of angry hundreds of fish.

Although the third reason is still up for debate, it is widely believed that close swimming allows fish to swim in a way that reduces friction and conserves energy.

The fourth reason is that swimming in schools can help tetras forage more effectively. One hundred eyes is definitely better than one or two sets when it comes to finding food and prey.

How To Maintain A 20-Gallon Aquarium?

If you are new to fishkeeping, a 20-gallon aquarium is a good starting point. It is neither too small or too large.

However, an aquarium is still only a small amount of water when compared to natural water bodies.

It’s also a closed system.

To ensure that your fish live the longest possible life, it is important to maintain the aquarium.

We will show you how to maintain a neon tetra 20-gallon aquarium in sections.

The Frequency Of Maintenance

It is not practical or desirable to clean every corner of an aquarium daily. It is not a good idea to clean everything at once as this could quickly destroy the good bacteria colonies.

You can disrupt the good bacteria colonies, which will cause the tank to lose its nitrogen cycle. This can lead to a spike in ammonia or nitrite levels.

Things You Should Do Daily

Perform a visual inspection of the tank at the beginning of each day to make sure that the filtration system is working properly, the lights work well, and that the temperature is correct.

Do a headcount to ensure that all fish are healthy and in good condition. When you are feeding them is the best time to count. It will be easier for them to count and observe at this time.

Once the fish have finished eating, take out the leftovers to ensure that the water remains clean for longer periods. You might notice that there is always something left unfinished.

Keep a note of any unusual patterns you find so that you can examine them and make improvements.

Here is a brief summary of the paragraph.

• Check filtration equipment
• Check the temperature
• Count and watch for fish
• Remove uneaten food
• Add to the water level
• Notes in a logbook

Things You Should Do Weekly/ BiWeekly

Water changes are not a one-size fits all rule. Hobbyists may advocate water changes every other week. Others believe it is sufficient to change the water every other week.

Water changes can be performed weekly or biweekly depending on how many you have. Make sure you add water to your tank that has been treated and, if possible, is aged.

The replacement water parameters should closely match the original tank water.

There are some things you need to do before changing the water. You should not change the water.

Cleaning is another task that you should do once a week or twice a week. You should begin by cleaning the tank’s exterior with a tank-safe, non-ammonia liquid cleaner.

To get rid of the algae buildup, shake the plants gently. To get rid of algae buildup, you can scrape the glass’s interior.

Wait for 5-10 minutes to let all gunk and debris settle to the bottom. Next, gently siphon the substrate.

Finally, do a partial water change.

Here is a brief summary of the paragraph.

• Cleanse the outside surfaces
• Remove all debris from plants
• Scrape inside glass
• Siphon the substrate
• Perform a partial Water Change

Things You Should Do Monthly

To ensure that nothing is harmful is being brewed, you should conduct water parameter tests at minimum once a month. The most important parameters to monitor include pH, nitrate and nitrite.

We recommend the API’s Freshwater Master Kit.

A liquid-based test is much more reliable than strips.

Don’t forget about testing the phosphate levels if your tank is suffering from algae.

Before performing a water alteration, you need to test the water parameters.

You can also trim the plants to ensure they don’t outgrow the tank.

Next, complete all of the tasks outlined in the biweekly/weekly schedule.

Don’t forget to keep a bucket of water from your tank for filter maintenance.

You should replace exhaustible media such as zeolite and activated carbon every month.

For mechanical media, rinse it with the water from the last water change. If the mechanical media becomes too clogged, you can replace it.

To prevent the loss of beneficial bacteria colonies, you must keep the media intact.

Here is a brief summary of the paragraph.

• Conduct water tests
• Trim the plants
• Complete the weekly/biweekly tasks
• Use Filter media

Things You Should Do Periodically

There are some things that you can do on an as-needed basis, in addition to the regular maintenance tasks. These include changing the light bulbs once a year or every six months.

If you have a canister filter, it is also worth inspecting the tubing of the air pump and filter. Use a filter brush to clean the intake of the canister filter.

If you have living plants, fertilize them as needed.

Here is a brief summary of the paragraph.

• Replace light bulb
• Inspect and maintain tubing
• Clear the filter intake
• Fertilize your plants

Frequently Asked Questions

What Are The Best Tankmates For Neon Tetras In A 20-Gallon Fish Tank?

The following would make ideal tank mates for neon Tetras in a 20-gallon fish aquarium:

• Endler’s guppies
• Snails
• Platies
• Barbs
• Mollies
• Glofish
• Zebra danios
• Hatchetfish
• Harlequin rasboras
• Chili rasboras
• Dwarf gouramis
• Corydoras catfish
• Zebra loaches
• Otocinclus catfish
• Kuhli loaches

How Many Neon Tetras In a 29-Gallon Tank?

We could easily house 16-17 neon Tetras in a 29-gallon tank, assuming that the average height of the Tetra is 1.75 inches.

If we apply Dick Mill’s rule that 12 inches of surface area is allocated for each inch of the fish’s body and assume they are 1-inch tall, then we could keep 30 neon tetras in 29-gallon tanks.

How Many Neon Tetras In A 10-Gallon Tank?

Divide 10 by 1.75 to get 5.7. We can also round it up to 5, or 6. In a 10-gallon tank, you can store 5-6 neon Tetras.

This is a decent amount! This is also the most you can keep for monitoring their schooling behavior.

How Many Neon Tetras In A 5-Gallon Tank?

Divide 5 by 1.75 to get 2.8. We can even round it up to 3. In a 5-gallon aquarium, you can keep 3 neon tetras. These fish must be kept in groups of six or more to feel at ease.

Final Words: How Many Neon Tetras In A 20-Gallon Tank?

A 20-gallon tank would be a good size for beginners. It is large enough to allow for mistakes, but not too big to make it difficult to tend to.

A 20-gallon fish aquarium can hold anywhere from 10-30 neon Tetras. It is not difficult to see that 10-30 is quite a wide range. But let me explain.

Stock 10-12 fish if you are a beginner in the hobby. Once you feel confident in your knowledge and experience, you can stock as many as 30 fish.

Remember, however, that the more fish you have, the greater the need for maintenance.