How many Harlequin rasboras in a 5-gallon tank?

In this post, we will discuss the topic “How many Harlequin rasboras in a 5-gallon tank”. We will also suggest some fish species other than Harlequin rasboras to occupy a 5-gallon tank.

How many Harlequin rasboras in a 5-gallon tank

A 5-gallon tank cannot fit any Harlequin rasbora. 5-gallon tank is less than the minimum required by Harlequin rasboras. They are schooling fish and thus, it is strongly discouraged to raise Harlequin rasboras in a 5-gallon tank. 

5-gallon tanks are classified as nano tanks. Thus, it is essential to pick these tank species very wisely. A 5-gallon tank is not as easy to maintain as many people may think. They require a lot of attention, as contaminants levels can quickly increase.

What you should know about Harlequin rasboras 

Harlequin rasboras are very peaceful and social fish that need to be kept in groups with at least 5 individuals. Their lifespan is 8 years when in ideal tank conditions. They are small fish that measure 2 inches maximum.

The minimum tank size adequate for Harlequin rasboras is 10-gallon ones. However, our suggestion is to opt for larger tanks. These fish are schooling fish that appreciate being members of greater groups. The universal rule for Harlequin rasboras is 2 gallons of water per inch of fish.

5-gallon tank dimensions

A regular 5-gallon tank dimension is 16 x 8 x 10 inches. However, it is also possible to find a variety of other shapes and dimensions. This tank general weight when filled is around 65 lbs.

Choosing fish for a 5-gallon tank

Nano tanks can have amazing looks. Although, the fish species choice must be conducted carefully considering some fish characteristics such as temperament, social needs, and schooling behaviour.

Keeping Harlequin rasboras in a 5-gallon tank is strongly not recommended. Here, we carefully chose some other possible fish species that would work in a nano tank with 5-gallon space better than Harlequin rasboras.

Pygmy Corydoras (Corydoras pygmaeus)

The Pygmy Corydorasare quite tiny catfish. They are very peaceful and should also be raised in schools of around 8 individuals. Similarly to the Celestial Pearl Danios, the Pygmy Corydoras also enjoy having hiding spots and vegetation around.

In a 10-gallon tank would be possible to keep up to 10 individuals. They are quite sensitive. Thus, it is important to keep all the water parameters well controlled.

Betta Fish (Betta splendens)

Betta fish are the top pick for freshwater nano tanks. They have very good-looking colours and shapes. Their temperament makes them perfect for this tank size. They can be raised alone and will not feel lonely or depressed.

A Betta fish should be the only individual of the species in a 5-gallon tank. They enjoy exploring around, thus it is recommended to provide plenty of plants and hiding spots. 

Guppies (Poecilia reticulata)

Guppies are also a nice pick for a 5-gallon tank. It is possible to keep 4 or 5 Guppies in a tank like this. They are happier in groups. However, keep in mind you should have a one-gender only group, as they can quickly overcrowd your tank.

Pygmy Corydoras (Corydoras pygmaeus)

The Pygmy Corys can also be a great pick for a 5-gallon nano tank. They are tiny fish that grow only to around 1 inch. Thus, it is possible to keep up to 5 individuals in a 5-gallon tank. They will assist you with keeping your tank clean and the high water quality. 

Neon Tetras (Paracheirofon innesi)

Neon Tetras can also be great fish for nano tanks. They measure up to 1.5 inches. Thus, the maximum number of individuals is 5. They are good-looking peaceful fish that require some plants and hiding spots.

Least Killifish (Heterandria formosa)

The Least Killifish is also a good option for 5-gallon tanks. However, it is only possible to keep 2 Least Killifish. They are tiny fish and measure up to 1.4 inches. They are easy fish to maintain and enjoy complex environments, with plants and decorations.

Celestial Pearl Danio (Celestichthys margaritatus)

The Celestial Pearl Danios easy fish to keep. They only grow to 1 inch and are very calm. Thus, they are really good fish for a 5-gallon tank, it is possible to keep around 5 individuals within this space. Celestia Pearl Danios are quite hardy fish and come in gorgeous colours.

Dwarf Pea Puffer

The Dwarf Pea Puffer is also a tiny fish species. They usually grow around 1.5 inches. They are awesomely good-looking fish and very popular. Due to their behaviour, the recommendation is to keep only one Dwarf Pea Puffer per tank.

5-gallon community tank combinations

It is also possible to consider some community combinations for 5-gallon nano tanks. Here are some community combinations with fish and non-fish species that would fit perfectly into your nano tank:

–       1 Betta + 1 Amano Shrimp + 1 Nerite Snail + 2 Killifish;

–       10 Cherry Shrimp + 5 Nerite Snails;

–       1 Betta + 2 Cherry Shrimp;

–       5 Chery Shrimp + 2 Thai Micro Crabs;

–       4 Celestial Pearl Danios (1 male and 3 females) + 2 Cherry Shrimp.

Tips for a 5-gallon tank

–       Fix a schedule to change the water;

–       Use high-quality filters and equipment;

–       Avoid overfeeding and overstocking;

–       Always consider the specific requirements and behaviours;

–       Provide enough plants and substrate.


In this post, we discussed “How many Harlequin rasboras in a 5-gallon tank”. We also suggested some fish species other than Harlequin rasboras to occupy a 5-gallon tank.

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

Frequently Asked Questions (FAQs): How many Harlequin rasboras in a 5-gallon tank

Can Harlequin rasbora live in a 5-gallon tank?

No, once they are schooling fish, they require to be in groups. However, a 5-gallon tank would only fit 1 Harlequin rasbora, which makes this size incorrect for Harlequin rasboras.

How many Dwarf rasboras can I put in a 5-gallon tank?

5-gallon tanks are not recommended for big schools of rasboras. Dwarf rasboras can grow up to 0.75 inches. Thus, it is possible to keep up to 5 or 6 Dwarf rasboras in a 5-gallon tank. 

How many Chili rasboras can I put in a 5-gallon tank?

Although 5-gallon tanks are not recommended for big schools of rasboras. Chili rasboras, similarly to the Dwarf rasboras, grow up to 0.75 inches. Thus, it is possible to keep up to 5 or 6 Chili rasboras in a 5-gallon tank. 

Are Chili rasboras hardy fish?

Yes, Chili rasboras are classified as hardy fish. They can tolerate slight variations in water conditions.

Do rasboras need a heater?

It is important to use a heater in your rasbora tanks as they are tropical fish and require warmer waters. Also, the heater will avoid temperatures instabilities.

What plants do rasboras like?

Rasboras, in general, enjoy well-planted tanks. Thus, some plant species you can consider are Java moss, Java fern, Duckweed, Amazon sword, and Cryptocoryne wendtii.


Stanton, L. 2021. How Many Rasboras Can You Have In a 5, 10 & 20 Gallon Tank?

Yang, A. 2020. Harlequin Rasbora Care: Size, Tank Mates, Breeding & More.

Edmond, A. Harlequin Rasbora: Everything You Need To Know.

Best Fish For a 5 Gallon Tank (And Small Tank Benefits).

Best Fish For A 5 Gallon Tank Stocking Ideas And Combinations You Can Use.

How Many Fish Can Be In A 5-Gallon Tank? Best Fish & Stocking Ideas.

Sheppard, M. 2021. 21 Best Fish For 5 Gallon Tanks (With Pictures).