How many fish can be in a 30-gallon tank?

In this article, we will discuss the topic “How many fish can be in a 30-gallon tank” and also know the best fish species to keep in a 30-gallon tank and some of their tank specificities.

How many fish can be in a 30-gallon tank

It is possible to safely keep a maximum of 30 small fish (1 inch) in a 30-gallon tank. The “one inch of fish per gallon of water” rule is maintained for a 30-gallon tank. However, if you consider having fish bigger than 3 inches, it is important to recalculate according to the size of the animals. This is because 10 1-inch fish are smaller than 1 10-inch fish. In addition, their needs are also different. It is always necessary to keep the fish biology and requirements in mind.

Usually, 30-gallon tanks are stocked with freshwater fish. Due to the lower maintenance and price in comparison to saltwater fish tanks for this size.

Fish size Myth

There is a myth that says the fish will only grow according to the size of the tank. This is nothing beyond an urban legend. This is very dangerous to your fish health. This limited growth occurs due to the waste and contaminants excess. Thus, the fish growth becomes stunted and fish stay smaller.

How to choose which fish can be in a 30-gallon tank?

Other factors than size must be considered when choosing fish for a 30-gallon tank. Some of the factors are listed below:

–       Fish species activeness levels;

–       Peaceful or aggressive and territorial temperament;

–       Schooling or solitary behaviour.

More active fish will require more space to explore and swim. Aggressive and territorial fish also need a bigger space to establish their territory and avoid intruders. In the case of opting for more territorial and aggressive fish species, having a well-planted tank with plenty of hiding spots could reduce the stress level of the fish, as they would have refuge and visual isolations from another fish territory.

Additionally, the fish species social behaviour is also important. If they are schooling fish, what would be the minimum school size to keep the fish healthy? It is always necessary to research these topics about fish species behaviour before choosing the fish for your 30-gallon tank. 

Advantages of a 30-gallon tank

Differently from nano-tanks, 30-gallon tanks are not so limited and are a very good option for beginner aquarists. 30-gallon tanks also have enough space to organize décor. Thus, they provide a high quality of life for your fish.

30-gallon tanks are also easier to take care of than bigger tanks. A regular 20% water change is usually enough for this tank size. 

What fish species can be in a 30-gallon tank?

Here are the top 8 most popular fish choices for a 30-gallon tank and a few of their specificities.

1.   Guppies

Guppies are tiny and very good for community tanks. They have some bright colours and can give an awesome look to your 30-gallon tank. Guppies would need at least 2 gallons per Guppy as they grow up to 2 inches. Thus, 15 guppies in a 30-gallon tank would be the maximum to be kept healthily.

Guppies are very fast breeders. Accordingly, consider not having male-female pairs. Also, guppies enjoy planted tanks. They are very low-effort to be maintained and are not picky eaters. In addition, they are also very sociable with other fish species and can live peacefully with tank mates. 

2.   Neon Tetras

Neon Tetras are also tiny species. They can frow up to 1.2 inches in length. Accordingly, it is recommended to have at least 1.2 gallons per Neon Tetra. The limit number of Neon Tetras in a 30-gallon tank is 20 to 25 fish.

As for schooling fish, they can live very peacefully in big groups and also in community tanks, being very nice tankmates.

They also enjoy well-planted tanks with a slightly high temperature. In general, they are also low-effort to be kept.

3.   Platies

Platies are also very peaceful fish and have a wide variety of colours. They can grow up to 3 inches. Thus, having at least 3 gallons per Platy is recommended. Consequently, a maximum of 10 Platies could be fit in a 30-gallon tank.

As peaceful fish, they can also live peacefully in a community tank with other small fish species. Although, they are also very active breeders. Thus, consider not keeping male-female pairs to not overpopulate your tank.

Similarly to Guppies and Neon Tetras, Platies are also low maintenance fish and also make awesome tankmates.

4.   Cory Catfish 

Cory Catfish are also an amazing tankmate to be kept in a community. They are bottom dwellers that can grow up to 2.5 inches. Thus, the maximum capacity of a 30-gallon tank is 10 to 12 Cory Catfish.

Due to their feeding behaviour, they assist aquarists n keeping the cleanliness of the tank, removing debris deposits from the bottom of the tank.

Differently from the 3 species above, they are more fragile to the water parameters and tank conditions. Thus, they require more attention regarding these features.

5.   Molly Fish 

There are about 40 different types of Mollies. The bigger ones can grow up to 4.5 inches. Correspondingly, the maximum number of Mollies in a 30-gallon tank would be 6. 

They are also very peaceful fish that live very healthily in a community tank. They are also low maintenance fish species and omnivores, meaning they are picky eaters.

6.   Bristlenose Plecos

The Bristlenose Plecos are also very peaceful fish that live on the bottom of the tank. They are quite big fish, they can grow up to 5 inches. Therefore, a 30-gallon tank capacity of Bristlenose plecos is 6 individuals.

As bottom feeders, similar to the Cory catfish, the Bristlenose plecos assist in keeping the tank clean. They also feed on debris and even on growing algae. They are not fragile as the Cory catfish and are also not picky eaters. 

7.   Cherry Barbs

Going back to the small fish. Cherry barbs can grow up to 2 inches in length. Thus, a maximum of 15 fish could be kept in a 30-gallon tank. As they are schooling fish, they prefer to be kept in big groups and are one of the most peaceful fish. They never provoke issues in a community tank.

They also require low effort to be kept and are very beginner-friendly species. They are not picky eaters and not fragile.

8.   Rainbowfish

The Rainbowfish are very colourful fish. However, they are not very small as the smallest type can grow up to 4.5 inches. Therefore, a total of 6 small Rainbowfish is the recommended limit for a 30-gallon tank.

This is also a very peaceful fish species and can be kept in a community tank without causing any issue. However, the minimum number to form a healthy Rainbowfish school is 6. Thus, for a 30-gallon tank, the Rainbowfish is recommended to be the only species. Additionally, they are quite fragile to water parameters and can become picky eaters.

What are the top 5 best combinations for a 30-gallon tank?

1.   4 Mollies, 4 Neon Tetras, and 2 Cory Catfish;

2.   10 Neon Tetras and 7 Guppies;

3.   5 Platies and 6 Guppies;

4.   2 Bristlenose Plecos and 4 Mollies;

5.   5 Cherry Barbs, 6 Neon Tetras, and 2 Bristlenose Plecos.


In this article, we answered the question “How many fish can be in a 30-gallon tank” and knew the best fish species to be kept in a 30-gallon tank and some of their tank specificities.

If you have any thoughts or doubts, feel free to drop us in a comment below!

Frequently Asked Questions (FAQs): How many fish can be in a 30-gallon tank

What kind of fish can you keep in a 30-gallon tank?

For smaller fish species, up to 5 inches, it is recommended to follow the “One inch of fish per gallon of water” rule. Thus, in a 30-gallon tank, species as Neon Tetras, Guppies, and Platies make colourful additions to well-planted tanks. They are very peaceful community fish species that will not cause issues in a 30-gallon tank. 

How many fish can you put in a 29-gallon tank?

Similarly to the 30-gallon tank, if you consider small fish species, you can follow the “One inch of fish per gallon of water” rule. Thus, if you consider 2 inches long fish, you could keep up to 14 fish in a 29-gallon tank.

Is a 30-gallon tank good? 

The answer to this question will depend on which species you are considering keeping in a 30-gallon tank. Smaller fish species can live very well in a 30-gallon tank. However, large-bodied fish could not live so well. Thus, consider the fish species when choosing the size and shape of your tank. 

How much gravel do I need for a tank?

The general rule for gravel is to have one pound of gravel per gallon of water. Thus, for a 30-gallon tank, it would be necessary a minimum of 30 pounds of gravel. Additionally, it is also necessary to consider the gravel quantity when calculating the fish quantity in your tank. 

Can a Betta fish live in a 30-gallon tank?

Yes, a Betta fish can live very well in a 30-gallon tank. There is not a maximum tank size recommended. However, it is important to provide a not too deep tank with plenty of hiding spots and plants. 

How many Tetras can I put in a 30-gallon tank?

The rule for small fish species is one inch of fish per gallon of water. Thus, if you consider 1.5 inches long Tetras, the maximum number of individuals would be 20.


Thomas, D. 2021. 30 Gallon Fish Tank Guide: Size, Stocking Ideas and More…

Stanton, L. 2021. 12 Best Fish For 29 & 30 Gallon Tanks (With Pictures).

30 Gallon Fish Tank: Setups, Stocking Ideas, Equipment And More… 2019.