How many Harlequin rasboras in a 30-gallon tank?

In this post, we will discuss the topic “How many Harlequin rasboras in a 30-gallon tank” and all steps of setting up a Harlequin rasbora aquarium. We will also list some community tank combinations.

How many Harlequin rasboras in a 30-gallon tank

A 30-gallon tank can fit 8 or 9 Harlequin rasboras. Harlequin rasboras are extremely schooling fish. Thus, they require being in groups of at least 5 individuals. Accordingly, a 30-gallon tank would provide enough room to guarantee the Harlequin rasboras wellbeing.

The space recommendation for Harlequin rasboras is around 2 gallons of room per inch of fish, and they measure 2 inches maximum. Thus, a maximum of 4-gallon space for a single Harlequin rasbora.

What you should know about Harlequin rasboras 

Harlequin rasboras are incredibly admired pacific fish. They are well-liked because of their notable vivid colouration design and great personality.

They do not demand knowledge as they are easy fish to have. Since they are shoaling fish, the suggestion is to maintain them in shoals of at least 5 fish. Though, they can live in reduced shoals also. 

Their lifespan is around 8 years. However, the average life expectancy is 5 years. They only grow up to 2 inches and have a rosy or orange diamond shape. 

What to feed Harlequin rasboras with

Harlequin rasboras are omnivores. Thus, in a tank, they must be fed with plenty of food items, from animal and plant sources. You can offer small flakes and pellets to create a basis for their diet. Then, you can also offer some bloodworms and Brine shrimp.

Setting a Harlequin rasbora tank 

Tank requirements are significant for fish well-being. Harlequin rasboras do not have complex requirements to follow as they are low maintenance fish.

Water parameters

Harlequin rasboras need warm water temperatures between 72 and 82 degrees Fahrenheit. Thus, it is indispensable to use a heater and a regulator in the aquarium. Moreover, pH levels range is between 6 and 7.8 and water hardness between 2 and 12 KH is ideal.

Tank size

Harlequin rasboras can inhabit smaller tanks. However, the minimum size is a 10-gallon tank. The recommendation of keeping them in larger groups requires larger tanks. Thus, they would act more naturally and will have guaranteed wellbeing.

Water filtration system

It is essential to keep a good filtration system. We recommend equipment that works automatically in the major 3 filtration schemes: chemical, biological, and mechanical. Additionally, this equipment should not be strong enough to generate fast currents in the tank. 

Plants & Substrate

The natural distribution area of Harlequin has sand and gravel substrate. Therefore, it is recommended to mix these tank substrates. 

Additionally, Harlequin rasboras habitat is heavily-planted. Thus, the recommendation is to provide loads of plants. These plants should be placed at the peripheric region of the tank. Otherwise, there will not be enough space for them to swim freely in the centre of the tank. 

These fish appreciate plants because they can hide and get protection from them and avoid competitors.

Who are good Harlequin rasboras tankmates?

Harlequin rasboras are incredibly peaceful fish. They are surely suitable selections for the community aquarium as they are compatible with several fish and non-fish species extremely easily. Harlequin rasboras will not perform any fin-nipping or other antagonistic attitudes.

Some of the best Harlequin rasboras tank mates are small peaceful fish species that have similar needs to the Harlequin rasbora and do well with dynamic swimmers.

–       Harlequin rasboras: Very important to natural shoaling behaviour;

–       Neon and Cardinal Tetras: Shoaling fish – 4-6 individuals minimum;

–       Corydoras: Peaceful bottom-dwellers. Not shoaling – small groups of 2-4 individuals;

–       Bristlenose Plecos: Peaceful bottom-dwellers;

–       Danios: Shoaling fish – 4-6 individuals;

–       Guppies: Active shoaling peaceful tiny fish – 6-8 individuals. 

Some invertebrates can be good tank mates to Harlequin rasboras:

–       Mystery snails: The cleaning crew, will not bother Harlequin rasboras

–       Cherry or Amano shrimp: Cleaning crew, they are not prone to bother any of their tankmates.

30-gallon tank dimensions

A regular 30-gallon tank dimension is 36 x 18 x 12 inches. However, it is possible to find various other forms and dimensions. The tank weight when filled is around 350 lbs depending on the amount of substrate and décor.

Advantages of a 30-gallon tanks

Contrarily from nano tanks, 30-gallon tanks are not so restricted and are a suitable choice for novice hobbyists. 30-gallon tanks also have plenty of space to organize decoration. 

30-gallon aquariums are also simpler to take care of than larger ones. A methodical 20% water renovation is generally sufficient for this aquarium size. 

Some other aspects than tank volume have to be pondered when selecting inhabitants for a 30-gallon tank. Some of these aspects are below:

–       Fish species activity intensities;

–       Fish temperament (Placid, calm, gentle, indifferent, peaceful, aggressive, semi-aggressive, or territorial);

–       Shoaling or solitary comportment.

More dynamic species will necessitate more room to investigate and travel around. Antagonistic and territorial fish also need a larger space to determine their territory and keep invaders away.

30-gallon tank community combinations with Harlequin rasboras

When deciding to go with larger tanks, it is possible to consider a community tank. Thus, it is important to keep in mind the fish needs and temperament. Here we draw a few possible combinations for 30-gallon community tanks with Harlequin rasboras. 

Here are some possible fish combinations for a 30-gallon tank with Harlequin rasboras are:

1.   4 Harlequin rasboras + 4 Neon or Cardinal tetras + 2 Cory catfish;

2.   4 Harlequin rasboras + 2 Bristlenose plecos;

3.   5 Harlequin rasboras + 6 Guppies + 4 Amano or Cherry shrimp;

4.    5 Harlequin rasboras + 6 Neon or Cardinal tetras + 4 Mystery snails;

5.   4 Harlequin rasboras + 5 Neon or Cardinal tetras + 2 Bristlenose plecos.


In this post, we discussed “How many Harlequin rasboras in a 30-gallon tank” and all steps of setting up a Harlequin rasbora aquarium. We also listed some community tank combinations.

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 30-gallon tank

How many gallons do Harlequin rasboras need?

The minimum tank size required by Harlequin rasboras is 10-gallon tanks. However, it is recommended to go for larger tanks, as these fish do better in bigger groups.

How many Harlequin rasboras can I put in a 55-gallon tank?

A 55-gallon tank has enough space to house around 13 to 15 Harlequin rasboras. This size of the tank is good as it can hold a big group of Harlequin rasboras plus enough tank features and even some tankmates.

What fish go well with Harlequin rasboras?

Various other small-bodied peaceful fish make great Harlequin rasboras tank mates. Some of them are small tetras, other rasboras, dwarf gouramis, small danios, and guppies.

Do Harlequin rasboras like water flow?

No, Harlequin rasboras are originally from areas with slow-moving waters. For this reason, they prefer a slow current in the tank.

Do rasboras eat shrimp?

No, rasboras nature is extremely peaceful. They are safe for shrimp, snails, and live plants.

How do you feed Harlequin rasboras?

It is possible to feed Harlequin rasboras using industrialized flakes and pellets on a diet basis, supplemented with live or freeze-dried animal proteins, such as some worms, brine shrimp, and newborn Daphnia.


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.

Stanton, L. 2021. 15 Best Tank Mates for Harlequin Rasboras (With Pictures).

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