How many fish in a 20 gallon tank should you keep?

When it comes to aquarium size, a 20-gallon tank is great for the beginner aquarist who has kept fish for a long enough period of time to want something larger than a 10-gallon aquarium.

Many people are unaware of how many fish in a 20 gallon tank can be added and this fairly depends upon the species, living habitat, and behavior of the fish.

However, I recommend going through this article and understanding what and how many different species of fish can you add to a 20 gallon aquarium?

You may keep a broad range of tropical fishes in a 20-gallon tank, including species with larger overall bodies and unusual mixtures of small-bodied fishes.

You can also keep species with larger overall bodies and spectacular schools of small-bodied fishes.

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Also notice that a 20-gallon long container may house more cattle than a standard 20-gallon container, making it the superior choice depending on the circumstances.

When it comes to keeping fish with unusual forms, such as angels, a 20-gallon tall tank is the ideal option in some situations.

Tropical fishes that can be kept are listed below. For most fishes, the rule of thumb is one inch of fish for every gallon of water.

This implies that you may have up to 15 one-inch fishes and up to 6 2.5-inch fishes in a twenty-gallon aquarium.

A correctly designed 20-gallon aquarium can accommodate some of the most popular tropical species, including fancy-goldfish, betta, mollies, platies, betta, danios, rasboras, barbs, small-gouramis, dwarf cichlids, cories, small-catfish, and even schooling fishes such as tetras.

These are some of the fishes that can be considered for the 20 gallon fish tank

Table of Contents

How many fish in a 20 gallon tank should you keep?

The majority of the species on the list above are suitable for a 20-gallon fish tank, while some fare better in slightly larger tanks, while others, like as ottos and bettas, may be kept in smaller (10-gallon) tanks.

Livebearers (guppies, mollies, platys), small loaches, plecos, and catfish (ottos, cories, bushynose, kuhli loach), fancy goldfish, smaller barbs (barbs, gold), schooling fishes (neon tetras), dwarf gouramis, danios, and dwarf cichlids are some of the finest fish to raise in a 20-gallon (blue rams, rainbow kribs, Apistos).

A 20-gallon fish tank with livebearers.

A 20-gallon aquarium is the most appropriate size for practically all tropical fish used in aquariums, including livebearers. It differs in both the amount of attention given to the fish and the size of the fish.

Livebearers are available in four different sizes ranging from 1.4 inches to 5.5 inches in length, with swordtails being the largest and fancy guppies being the smallest of the four.

The result is that you can put more beautiful guppies (8 to 10) and only a pair of swordtails into each of your twenty-gallon fish aquariums.

When it comes to upkeep and maintenance, a 20-gallon tank should be plenty for dealing with everything the livebearers throw at you.

Despite the fact that they are more difficult to care for than Betta, they are still inferior in size to larger fishes such as African cichlids and Central American cichlids, as well as South American cichlid species such as Angels and Discus.

In any case, if you decide to maintain livebearers in your 20-gallon, I recommend starting with guppies and platys, which grow smaller and have a lower bioload than other species. This is especially true if you are new to aquarium maintenance.

Do not try to raise ornamental fish unless you have a great deal of expertise with them.

In addition, keep in mind that swordtails and bigger mollies, such as the sailfin, may need to be transferred after they reach their maximum size; the amount of hostility increases when larger livebearers are maintained in a small enclosure.

So, the next is about the Guppies and how many fish in a 20 gallon tank full of guppies should you add?

How Many Guppies Fit in a 20-Gallon Fish Tank?

The ratio of guppy to water is one for every two gallons of water you have, which means a 20-gallon aquarium may accommodate up to ten people.

Nonetheless, to guarantee that each fish has ample swimming room, especially if you intend on adding plants and other decorations to the tank or breeding your fish in it, I recommend keeping between 6 and 8 individuals in the tank.

Guppies in a 20 gallon fish tank
Per Harald Olsen, CC BY 3.0, via Wikimedia Commons

In addition, if you intend to keep your guppies with other tankmates, such as other livebearers or bottom-dwellers, a group of between 6 and 8 is the best size.

How Many Platys to add in a 20 gallon tank?

Platies, like guppies, are not very huge fish, and you can keep up to ten of them in a 20-gallon fish tank without a problem.

Because the species is a cheerful fish that appears to love being in large groups, a group of 8 to 10 individuals is ideal, but any number between 8 and 10 is preferable.

platys in a 20 gallon fish tank

As a general rule, you should retain three times as many females as males in a 1:3 ratio, especially if you wish to breed your school. So, if you have eight platys, six of them should be females and two should be males.

Note that the quantity will vary depending on whether you wish to keep your platys with other fish or not. Also, keep in mind that livebearers are quite sensitive to filtration, so make sure you have a reliable unit.

So, the next is about the mollies and how many fish in a 20 gallon tank full of mollies should you add?

How many mollies can fit in a 20 gallon fish tank?

However, other livebearers (platys and guppies) will do better in a 20-gallon tank than mollies, as I have already indicated. Furthermore, bigger breeds such as sailfins should not be kept in an aquarium of this size.

If you really must have mollies in your tank, I recommend just two in a 20-gallon tank at the most.

If you feel that your fish tank is too empty and that it needs a bit more movement, you may couple them with a school of little fishes such as neon tetras to fill the gap.

Black mollies in a 20 gallon fish tank
Marrabbio, CC BY-SA 3.0, via Wikimedia Commons

I’m sure you’re already aware that mollies love hard water with a slight saltiness to it, and you might be concerned about keeping them alongside neon tetras.

You may be confident that adding some salt to your fish tank will not cause your neons any discomfort.

How many swordtails to add in a 20 gallon aquarium?

Swordtails, like mollies, have a tendency to gravitate toward the bigger livebearers in terms of size. As a result, a 20-gallon fish tank can only accommodate a pair (maximum of three).

Fortunately, they get along well with little schooling fish, though they do need mildly alkaline water, so you may mix them in with a school of neon tetras if you want to increase the amount of activity in your aquarium.

Please keep in mind that swordtails may grow to be 5.5 inches in length and create a significant amount of bioload, so you may want to consider transplanting them if they become too large for your 20-gallon tank.

Some Catfish, Loaches, and Plecos for a 20-Gallon Fish Tank

If you have a 20-gallon fish tank, you can also put in some bottom-dwelling fish. Livebearers are usually found in the middle and the top of a fish tank.

A 20-gallon tank is a right size for cory catfish and bristlenose plecos, both of which fit well. South American natives: Both species come from there. They’re both easy to keep and care for, and they live there.

The dwarf sucker catfish, also known as Otocinclus, is another South American fish that lives at the bottom of rivers and lakes in that area.
The Kuhli loach can also fit in a 20 gallon tank.

It’s great if you want something different from your catfish and plecos and don’t want to keep the same fish. It’s a fish that looks a little like an ill. It lives in Indonesia and the Malay Peninsula.

How many cories should you add in a 20 gallon tank?

You may keep up to four cory catfish in a 20-gallon fish tank (1 for every gallon of water), but be aware that there are various species of the same family, some of which grow larger and are more delicate than others, so choose wisely.

In comparison to skunk cory, you can fit more pygmy cory in a 20-gallon tank since they are smaller and create less bioload.

In addition, if you cover every inch of your substrate with stem plants, you will not be able to retain as many people as you would like in your aquarium.

Corydora fish in a 20 gallon tank
A Picture of Corydoras

My favorite types of cory catfish are the pygmy and albino catfish. They’re small but hardy and can live even in less than ideal conditions, so I would keep them in a 20 gallon tank.

Your 20-gallon container will also accommodate Julii and other lesser-known (or more readily available) species.

However, because they are not well investigated in an aquarium setting, it is preferable to keep them in a larger fish tank where the situation can be more easily managed and maintained.

Also, bear in mind that corys do well in groups, so if you want to keep them with other fishes, you may want to consider a larger fish tank to accommodate them.

How many Bristlenose Plecos can fit in a 20-gallon aquarium?

Bristlenose plecos are among the tiniest aquarium catfish, ranging an average size of 3 to 5 inches.

One bristlenose may be kept in a 20-gallon tank, preferably one that is longer rather than one that is tall, depending on the fish that you maintain with it.

Bristle pleco for 20 gallon fish tank
A Picture of Bristlenose Pleco

In order to lessen the cleaning and maintenance burden on your bristlenose, attempt to pair it with tankmates that have a lower bioload than it to limit waste production.

Furthermore, if you are unfamiliar with the care of tropical fish, you should refrain from maintaining a bristlenose pleco in such a small aquarium. Instead, go for a 30-gallon fish tank to have a more comfortable fish-keeping adventure.

A 20 gallon fish tank can hold how many dwarf sucker catfish (Otocinclus)?

Thousands of shoals of Otocinclus catfish may be seen in the wild, indicating that the fish are gregarious. It is recommended that at least 6 fish be kept in your aquarium.

They will fit in a 10-gallon tank despite their small body size, with up to 10 individuals being optimum in a 20-gallon tank due to their small body size.

Dwarf suckermouth catfish for 20 gallon aquarium
Here is a Picture of Dwarf suckermouth catfish

As many as 15 Otos may be desired, with a smaller number being only useful if you want to keep them in a group tank with others.

Small bottom feeders like dwarf suckers are an excellent alternative to bristlenose pleco in a 20-gallon aquarium, especially for beginner fish keepers who want a bottom feeder that will eat algae.

How many Kuhli Loaches to add in a 20 gallon tank?

In order for each pair of kuhli loach to survive, they require at least 15 to 20 gallons of water, making them the most appropriate fish to keep in a 20-gallon aquarium.

Despite the fact that the fish may grow up to 4 inches in length, they are quite calm and don’t require a lot of additional areas for turf formation to survive.

kuhli loach for 20 gallon fish tank
A Picture of Kuhli loach

One thing to keep in mind is that kuhli loaches have a tendency to sift and burrow themselves into the substrate, so a sandy tank foundation is essential.

Besides that, they are nocturnal, quite timid, and maybe rather reclusive creatures. They scurry below tank decorations or bury themselves if there is fine gravel or sandy substrate in the tank when they are alarmed.

How about a 20-gallon tank full of goldfish?

In spite of the fact that goldfish are one of the most regularly kept decorative fish in aquariums, they have throughout the years experienced the consequences of living in cramped quarters.

I’m almost out of fingers and toes trying to keep track of how many times I’ve seen or heard about a goldfish grown in a bowl.

Goldfish in 20 gallon fish tank
A Picture of Goldfish in Aquarium

What the majority of these hobbyists fail to realize is that a fully grown common goldfish may reach 11 inches in length, whilst the smaller fancy goldfish average 4 to 7 inches in length, making them only suited for tanks of 20 gallons or bigger.

If you like goldfish here is an another variety of it and is commonly called as the bighead goldfish (Oranda Goldfish) that is very unique when compared to other fishes.

How many goldfish to add in a 20 gallon fish tank?

First and first, I’d want to point out that most goldfish continue to develop throughout the majority of their lives, which means they should not be maintained in a fish tank under any circumstances.

Nonetheless, they are quite popular all around the world, and it would be insane to urge you to refrain from purchasing one.

Having said that, the majority of fancy goldfish raised in captivity is between 1 and 4 inches in length, which means that a single individual may live peacefully in a 20-gallon aquarium.

However, if you intend to maintain more than one goldfish, as is generally the case, you will probably need to invest in a larger fish tank. For every goldfish that you add to your aquarium, you should set aside an additional 10-gallons of water.

Another thing to keep in mind is that goldfish create a lot of waste, which is not desired in smaller tanks unless you have a very effective filter system in place.

Barbs in a 20-gallon fish tank, what’s the deal?

Known as barbs, they are a tropical fish family that originated in Asia and is widely kept in aquariums. Barbs are a diverse group of fish that, like most other groups of fish, come in a variety of sizes and care requirements.

Every one of these fish is a social creature that must be kept in groups of at least 5 other individuals. As a result, the size of the fish tank is critical in ensuring that your barbs are comfortable and thrive.

cherry barbs for 20 gallon fish tank
Brian Gratwicke, CC BY 2.0, via Wikimedia Commons

A 10- to 20-gallon aquarium will hold small species such as cherry and gold barbs, but bigger species such as the tiger, rose, and black ruby barbs, as well as Deninsonii, will require an aquarium of at least 30 gallons, and an aquarium of at least 55 gallons when fully mature.

How Many Cherry Barbs can be added in a 20 Gallon fish tank?

The smallest tank that is advised for cherry barbs is a 20 gallon tank.

Because cherries, like all barbs, are a schooling species, they must be housed in groups of at least five to avoid becoming dispersed.

According to my personal experience, the optimal amount of cherry barbs for a 20-gallon tank is between 6 and 8 cherry barbs, depending on the species you intend to maintain with them.

How Many Gold Barbs Are There in a 20 Gallon Tank of Gold Barbs?

Cherries are beautiful, but gold barbs are even more so, and they are highly popular in the aquarium hobby. When compared to cherry barbs, golden barbs are distinguished by their distinctive yellow-gold coloration.

Because they are a schooling species, as you may have guessed, they should be kept in groups of at least five individuals. Because of this, you may (and should) keep anywhere from five to eight gold barbs in a 20-gallon tank.

Considering that male gold barbs are territorial, you should provide three gallons of tank space per fish in a 20-gallon aquarium. This means that a 20-gallon aquarium can accommodate 6 to 8 gold barbs.

Is It Possible to Have Schooling Fish in a 20-Gallon Aquarium?

20-gallon tank or less is required. The fact that they take up such a small amount of space in the fish tank allows you to keep a big number of them or mix them in with other fish in the tank.

Tetras and white clouds are two of the greatest schooling fish available. However, your minnow will thrive even in a cold water tank, but the neons require the type of atmosphere seen in most tropical fish ponds.

Neon tetras look very beautiful especially in a fish tank with live plantation and the next is about how many fish in a 20 gallon tank with neon tetras should you add?

Can you have a 20 Gallon tank full Of Neon Tetras?

For neon tetras, the general rule of thumb is to stock one gallon of water for every inch of fish you have in your tank. Due to the fact that tetras have a maximum length of one inch, a 20-gallon fish tank may hold up to 20 individuals in total.

You may want to limit the number of neons in your aquarium to 10 or so if you want to maintain them with other tropical fish in the same tank with them.

neon tetra in 20 gallon fish tank
úlfhams_víkingur, CC BY 2.0, via Wikimedia Commons

In addition, keep in mind that neons are extremely sensitive to water quality and should only be used in an aquarium that has been completely cycled.

With regard to their preferred environmental conditions, they appear to favour somewhat acidic water that has been darkened with tannins similar to what they would find in the wild.

How Many White Clouds should you add in a 20 Gallon fish tank?

White cloud minnows, like neon tetras, are exceedingly small and take up very little room in the fish tank they are kept in. You may keep as many as 25 individuals in a 20-gallon tank, however, a smaller number is recommended if you are keeping them with other fish.

As previously said, white clouds are highly versatile and will thrive even in cold water, making them excellent companions for goldfish, zebra danios, and weather loaches, among other fish species.

Danios in a 20-gallon fish tank: is it possible?

Danios are resilient fish that are fairly widespread in the hobby of aquaculture. They are good for novices since they are simple to maintain and can easily be paired with other fish, not to mention that they are well-suited for tiny aquariums such as a 20-gallon.

Despite this, please keep in mind that there are various species of danios, and you want to introduce smaller species that will fit into your 20-gallon tank. Fortunately, zebra danios and heavenly pearl danios are both well-suited for this purpose and are commonly accessible in stores.

How Many Zebra Danios Can You Fit in a 20 Gallon Tank?

Zebra danios, like neon tetras, are schooling fish who love to be housed in big groups where they can be seen and heard. They are also highly active when kept in large groups.

As a result, regardless of the size of your aquarium, you should include at least 6 people.

The same guideline that applies to other schooling fishes will still apply to zebra danios, which is that you should keep a gallon of water for every inch of fish in your aquarium. So you may have up to 12 (one and a half inches) of them in your 20-gallon container.

As a result, two schools of zebra danios, each with six members, would be enough, however, if you have other fish in the tank, you may choose a single group of the fish.

So, the next is about the Guppies and how many fish in a 20 gallon tank full of guppies should you add?

How many Celestial Pearl Danios can be added in a 20 gallon fish tank?

While they are more expensive than Zebra danios, Celestial Pearl Danios are really attractive fish that are not difficult to care for and will fit comfortably in your 20-gallon tank.

The ideal number of CPDs to keep in a 20-gallon aquarium is 25, but if you’re keeping them with other fish, you may want to keep a smaller number.

Celestial Pearl Danios in 20 gallon fish tank
A picture of Celestial Pearl Danios in Aquarium

They are flexible and will live in a variety of water conditions. They also have a mild disposition, which makes them suitable for use in community aquariums.

For those of you who wish to keep them with other fish, I highly recommend pairing them alongside corydoras catfish, both of which will fit easily in your 20-gallon aquarium.

Gouramis in a 20-gallon fish tank, is it a possibility?

If you’re seeking vibrant aquarium fish that are tiny in size, easy to maintain, and suitable for beginning aquarists, a few gouramis are almost certain to pop up in your search results.

Gouramis are appreciated for their potential to be the focal point of aquariums since they come in a variety of vibrant colors, with males being particularly vibrant. For 20-gallon tanks, fish with relatively small bodies, like tetras, are best kept alongside schooling fishes.

The honey and dwarf gouramis are two gourami species that I would recommend maintaining in a 20-gallon tank because of their tiny body size and ease of maintenance when compared to rarer varieties such as the licorice and paradise gourami.

Remember that betta is members of the gourami family and that they do best in tanks ranging from 10 to 20 gallons in size, however, most hobbyists consider them to be independent of the other members of their species.

Most beginners in fish keeping choose honey gourami and now let us understand how many fish in a 20 gallon tank full of honey gouramis should you add?

How Many Honey Gourami can be added in a 20-gallon fish tank?

Honey gourami is more tranquil than the other members of their family, which means you may maintain more than one without having too many problems with violence and territoriality.

Honey gouramis are less irritable than dwarfs, and if the tenacity of betta is anything to go by, they are virtually saints compared to them.

Pearl gourami in 20 gallon fish tank
Image by SuperJew from Commons Wikimedia

The number of honey gouramis in your fish tank should be three or four, in my opinion. When it comes to space, a pair is preferable, although they are typically hesitant and only become more confident when they are among other people.

Mixing yellow and red ones, for example, can provide a little diversity to your collection.

A 20 gallon aquarium can hold how many dwarf gouramis?

Although dwarf gouramis display more of the renowned feistiness of the family than honeys, you should be able to keep up to three individuals in a 20-gallon aquarium, even with a school of eight to ten neon fish.

A gallon of water should be available for every inch of your dwarf gourami’s body, thus if you have a trio of 3-inch fish, such as dwarf gouramis, a 20-gallon tank will be more than plenty for your group.

Even a pair of dwarf gouramis with eight neon tetras will leave enough space at the bottom of your fish tank for a couple of cory cats to roam about in.

Cichlids for a 20-gallon fish tank?

Those of you who have only seen enormous Central American and African cichlids, as well as Angels and Discus from South America, maybe wondering how any of these fish will fit in a 20-gallon fish tank.

It turns out that there are smaller cichlid species, commonly referred to as dwarf cichlids, that have generally tiny bodies and are therefore suitable for aquariums as little as 20 gallons.

Although the majority of dwarf cichlids described by aquarists are members of the Apistos and Rams families, the term is not precisely defined and can refer to any cichlid between 3 and 3.5 inches in length, including Julidochromis and rainbow Kribs from Africa, as well as Apistos and Rams from South America.

How Many Julidochromis in a 20 gallon tank should you add?

Julidochromis are a 3-inch fish that are ideal for beginners who want to get their feet wet in the world of African cichlids. Swim vertically, sideways, and upside-down in order to stay near to surfaces and hiding locations, which is a rare capacity for a fish of their size.

A 20-gallon tank may accommodate 3 to 6 Julidochromis as long as you give them adequate plant cover, rock formations, caves, and hiding places.

Also, bear in mind that, as the majority of other members of the Cichlidae family, these dwarfs are aggressive, but at a lower level of intensity, which means that if you decide to keep them, you should use caution when handling them.

How many German Blue Rams can fit in a 20 gallon aquarium?

A 20-gallon fish tank or more is recommended for German blue rams, which are magnificent, brightly colored cichlids that thrive in a vibrant environment. Because GBRs are bottom-dwelling fish, it is preferable to place them in a long tank to allow your GBRs more floor area.

In your 20-gallon tank, you may keep a single ram or a pair of rams together with other fish such as dwarf cories or tetras. Also acceptable is the addition of shrimp, such as Amanos, provided that they are large enough to avoid fitting into the GBR’s mouth.

Finally, if you want to maintain more than one male ram, it’s better to keep them in a tank that’s at least 40 gallons in size, because, like all cichlids, they can display territorial and aggressive behavior at certain times.

So, the next is about the rainbow kribs and how many fish in a 20 gallon tank with rainbow kribs should you add?

How many Rainbow Kribs should you add in a 20 gallon fish tank?

Even while a 20 Gallon Kribensis cichlid does not require a large aquarium to remain healthy, the size of your aquarium may have an impact on the stress levels and overall happiness of your fish.

The ideal tank size for your kribs should be 20 to 30 gallons in capacity. An adult pair will fit easily in your 20-gallon tank when maintained alone, with the additional room being used to control territorial tendencies.

If you must keep your rainbow kribs with other fish, pair them with little schooling fish such as tetras or calm bottom-dwellers like as cories to keep them company.

How Many Apistogramma Cichlids Should you Keep in a 20 Gallon Tank?

Apistos are excellent cichlids for keeping in a communal tank. Due to the fact that they are a bottom-dwelling species, they will get along well with any species that does not compete for vital tank space with them.

Because of this, a long and broad tank is the ideal choice for providing your Apistogramma with its own region to claim. It is also best to keep them alongside species such as Tetras, pencil fish, and other species that prefer to swim in the middle or near to the top of their tank.

Apistos are a kind of plant that grows to a maximum height of 3 to 3.5 inches and is endemic to South America.

Because of this, they simply demand a tank that is greater than 15 gallons in capacity, which means your 20-gallon tank falls inside their comfort zone.

Apistogramma is little fish that may be kept in a 20-gallon tank (one gallon for every inch of fish). They like to live in groups of two or three, with one male and two (or more) females and will fit in a 20-gallon tank nicely.

So, I hope this article was helpful for you in order to make the right choice on how many fish in a 20 gallon tank can be added. I always advice to allocate the suggested tank size in order to provide a better living environment for your fishes.

Happy fish keeping!

Hey, I am Praful Kharade, a Blogger, a Data scientist, and the Founder of Planet Fish. This is one of my Hobby Blogs that focuses on Aquatic animals, Reptiles, and Fish Keeping.

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