Harlequin Rasbora Care: Complete Guide For All Fish Keepers

Harlequin Rasboras, with their striking black triangular patch, are really popular among aquarists worldwide. If you’re considering adding these beautiful fish to your aquarium, you’re in the right place! 

In this article, we’ll dive into the essentials of caring for Harlequin Rasboras, so keep reading to find out everything you need to know!


Harlequin rasboras are an excellent option for beginners due to their hardy nature and easy care. They are schooling fish and thrive best in groups of at least six. Ideal tanks should be 10 gallons or larger with plenty of plant cover, and more length than height.

These tropical fish need a temperature between 72-81°F and a pH range of 6.0-7.8. Harlequin rasboras are omnivorous; while they can consume a range of foods, a diet predominantly based on high-quality tropical flakes or micro pellets is advisable.

Properly cared for, harlequin rasboras can live up to 5-8 years.

For tank mates, opt for peaceful and non-aggressive species that share similar environmental requirements. Consider tetras, corydoras, guppies, dwarf gouramis, and yes, zebra danios make a great choice too.

Are Harlequin Rasboras Easy To Keep?

Harlequin Rasboras are incredibly easy to care for, making them a perfect choice for fish lovers of all levels. Their friendly nature and simple maintenance requirements make them a delightful addition to any fish tank.

When it comes to temperament, these small fish are peaceful and get along well with other tank mates. That’s why they’re a great fit for community tanks, where they happily coexist with other fish without any territorial issues.

And luckily, these little guys aren’t picky eaters, so providing them with a balanced diet of high-quality flakes or pellets is all it takes to keep them in shape. Be sure to switch up their meals to ensure they get all the necessary nutrients.

(Now you know harlequin rasboras are easy to take care of! Here are 15 of the easiest fish to care for, rated by fishkeepers!)

NameHarlequin Rasbora (Paracheirodon axelrodi)
Cost$3.00+ Per Fish
OriginSouth East Asia (Malaysia, Singapore, Sumatra, Thailand)
Care LevelEasy
Lifespan5-8 Years
Size2 Inches
Tank Size10 Gallons
FeedingFish Flakes, Live Food, Blanched Vegetables
Community Tank Yes
Tank LevelMid Level
PlantsJava Fern, Anubias, Amazon Sword, Java Moss, Water Wisteria
Tank MatesDanios, Ender’s Livebearer’s, Guppies, Mollies, Neon Tetras, Platies, Rummy Nose Tetras, Swordtails, White Cloud Mountain Minnows, Cardinal Tetras
Breeding TypeEgg Layer


Harlequin Rasboras attract fish enthusiasts with their attractive appearance. Their sleek and slender body features a shimmering silver color on the lower half and a vibrant orange-to-red hue on the upper half.

Additionally, they have a black wedge-shaped spot just behind their gills, adding a touch of elegance to their overall look. Because of this unique marking, they truly stand out in any aquarium.


In terms of size, Harlequin Rasboras are relatively small, making them a great fit for various tank sizes. On average, they grow to about 2 inches in length. And due to their compact size, they thrive well in community tanks and can easily get along with other fish.


Harlequin Rasboras are known for their peaceful and sociable nature. They actively swim, and, when kept in groups of at least six, they show delightful schooling behavior. 

Watching them swim in harmony is absolutely beautiful, adding a sense of peace to any aquarium. Their peaceful personality also makes them excellent tank mates for other non-aggressive fish types.


Harlequin Rasboras have a good lifespan, typically living for 5 to 8 years with proper care. To ensure their well-being, create a suitable home that mimics their natural environment. Use a well-planted tank with hiding spots and space to swim.

In addition to that, maintaining good water quality is crucial for your Harlequin Rasboras’ lifespan. Change the water regularly and use a reliable filter to keep it clean and safe for them. And when it comes to their diet, make sure to feed them a balanced meal and mix up their diet to keep them happy and healthy.

Water Parameters

When it comes to Harlequin Rasboras’ water parameters, it’s essential to maintain a suitable environment for their well-being. 

NameHarlequin Rasbora
Tank Size10 Gallons


Harlequin Rasboras can thrive in a pH range of 6.0 to 7.8, which is slightly acidic to neutral. Keeping the water within this range ensures their comfort and health.


To promote the well-being of your Harlequin Rasboras, it’s important to maintain the water temperature within the range of 72 to 81°F, which mimics their natural habitat.

Water Hardness

Water hardness is another crucial factor. Harlequin Rasboras can adapt to a moderate range of hardness, and between 2 to 15 dGH is suitable for their well-being.

Tank Size

To ensure your Harlequin Rasboras’ happiness, it’s essential to provide them with a tank that is 10 gallons or larger.

By choosing the recommended tank size, you provide your Harlequin Rasboras with enough swimming space and room to explore. Additionally, a larger tank helps reduce stress and encourages their natural behaviors.

Also, with the right tank size, you can create a comfortable and interesting environment for your Harlequin Rasboras.

Harlequin Rasbora Care Sheet

There are so many great and colorful fish you can add to your tank as well as harlequin rasboras!

What Do Harlequin Rasboras Like In The Wild?

Harlequin Rasboras are small, schooling fish that are native to the freshwater streams and rivers of Southeast Asia. They’re found in a variety of habitats, including slow-moving streams, fast-flowing rivers, and even rice paddies.

The water in their natural habitat is typically soft and acidic, with a pH of 6.0 to 7.8. The temperature of the water varies depending on the location, but it’s generally warm, ranging from 72 to 81°F. 

The substrate in Harlequin Rasboras’ natural habitat is typically made up of sand or gravel. There are also usually plenty of plants, rocks, and driftwood in the water, providing them with hiding places and food.

Harlequin Rasboras’ diet in the wild consists of small insects, worms, and crustaceans. They’re also known to eat algae and other plant matter.

How To Setup A Tank For Harlequin Rasboras 

Setting up your Harlequin Rasboras tank can be challenging, especially if you don’t know where to start. So, here are some of the steps to ensure your success.

Choosing a Tank

Choose a tank that’s large enough for your Harlequin Rasboras. A 10-gallon tank is a good size for a small group of six fish. If you plan on keeping more fish, you will need a larger tank.

Marina LED Aquarium Kit, 10 gallon
  • 10 U.S. gallon glass aquarium

Adding Substrate

Add substrate to the bottom of the tank. Harlequin Rasboras prefer a soft, sandy substrate. You can also add some rocks or driftwood to the tank for added decoration.

Fluval 12693 Plant and Shrimp Stratum for Freshwater Fish Tanks, 4.4 lbs. – Aquarium Substrate for Strong Plant Growth, Supports Neutral to Slightly Acidic pH
  • Facilitates Rapid and Beneficial Colonization: Its porous structure enables swift colonization of beneficial nitrifying organisms, fostering a healthy aquatic environment crucial for the well-being of aquarium inhabitants

Adding Plants

Plants are essential for Harlequin Rasboras. They provide the fish with hiding places and help to keep the water quality high. You can add a variety of plants to your tank, including Anubias, Java Fern, and Cryptocoryne.

Setting Up a Filter

A filter is essential for keeping the water in your tank clean and healthy. There are many different types of filters available, so you can choose one that fits your needs and budget.

Aqueon QuietFlow 10 LED PRO Aquarium Fish Tank Power Filter For Up to 20 Gallon Aquariums
  • LED indicator light flashes when water cannot pass through the cartridge, generally indicating it’s time to change the cartridge

Add a Light

Harlequin Rasboras don’t need a lot of light, but a small light will help to stimulate their natural behavior.

Adding Water

Once you have added the substrate, plants, and filter to your tank, it’s time to add water. Use water that’s been treated with a water conditioner to remove chlorine and chloramine.

Conditioning the Water

After you have added the water, you need to condition it. This means adding a product that’ll help to remove any harmful chemicals from the water. There are many different water conditioners available, so you can choose one that fits your needs.

Seachem Prime Fresh and Saltwater Conditioner – Chemical Remover and Detoxifier 250 ml
  • POWERFUL TREATMENT: Seachem Prime is a complete and concentrated conditioner for both freshwater and saltwater fish tanks, working hard to remove chlorine and chloramine.

Add a Heater

Harlequin Rasboras prefer the water temperature to be between 72 and 81 degrees Fahrenheit. A heater will help to keep the water temperature consistent.

Tetra HT Submersible Aquarium Heater With Electronic Thermostat, 50-Watt, 2-10 Gallon
  • All Tetra HT heaters have indicator lights to let you know when the heater is on. It will be red when heating and green when the proper temperature has been reached..All Tetra HT Heaters will shut off if an electrical short is detected for your safety.

Testing the Water

Once the water has been conditioned, it’s important to test it for ammonia, nitrite, and nitrates. These are three harmful chemicals that can build up in the water and harm your fish. You can test the water with a water testing kit.

API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, White, Single, Multi-colored
  • Contains one (1) API FRESHWATER MASTER TEST KIT 800-Test Freshwater Aquarium Water Master Test Kit, including 7 bottles of testing solutions, 1 color card and 4 tubes with cap

Adding Fish

Once the water has been tested and the levels of ammonia, nitrite, and nitrates are safe, you can add your Harlequin Rasboras to the tank. Be sure to add them slowly so that they have time to adjust to the new environment.

(If you’ve never setup a fish tank before, then here’s a complete guide on what you need to do!)

Male Vs Female Harlequin Rasboras 

Here is an in-depth explanation of the differences between male and female Harlequin Rasboras:


Male Harlequin Rasboras are slightly larger than female Harlequin Rasboras. Male Harlequin Rasboras typically grow to be about 2 inches long, while female Harlequin Rasboras typically grow to be about 1-1.5 inches long.


Male Harlequin Rasboras are known for their vibrant colors. They have a larger and more pronounced black triangle on their back and a reddish-orange stripe that runs down their sides. Female Harlequin Rasboras are more brownish, but they still have a black triangle on their back.


Male Harlequin Rasboras are more active and aggressive than female Harlequin Rasboras. Also, Male Harlequin Rasboras will often chase each other around the tank.

On the other hand, female Harlequin Rasboras are calmer and spend most of their time swimming around the tank in groups.

Harlequin Rasboras Diet

Harlequin Rasboras are omnivores, which means they eat both plants and animals. Their diet should consist of a variety of foods, including flakes, pellets, live food, and frozen food.

Flakes and pellets are a good staple diet for Harlequin Rasboras. They should be high in protein and contain other essential nutrients. So, make sure to feed your Harlequin Rasboras flakes or pellets twice a day.

Live food, such as brine shrimp, daphnia, and bloodworms, is a good source of protein and other nutrients for Harlequin Rasboras. It can also help to stimulate their natural behavior. As for when to feed your fish live food, you can give it to them once or twice a week.

Frozen foods, like brine shrimp, daphnia, and bloodworms, are also good sources of protein and other nutrients for Harlequin Rasboras. They’re a bit more convenient than live food because they can be stored in the freezer and thawed out when needed. Just like live food, you can give them to your fish once or twice a week.

TetraMin Plus Tropical Flakes, Cleaner and Clearer Water Formula 7.06 Ounce (Pack of 1)
  • TROPICAL FORMULATION: Highly digestible flake blend for use as staple food for all tropical fish.
  • PLUS SHRIMP: With natural shrimp for maximum flavor – a natural attractant for aquarium fish.
  • FOR ALL TROPICAL FISH: ProCare blend helps support your fish’s immune system for optimal health and long life.
  • CLEAR-WATER FORMULA: Won’t cloud water when used as directed.
  • COLOR ENHANCING: Specialized, high-protein fish flake in a formula that enhances your fish’s naturally brilliant colors.

Harlequin Rasboras Tank Mates 

Harlequin Rasboras are peaceful and sociable, making them great tank mates for various other fish. Here are the 10 best tank mates for Harlequin Rasboras and the reasons why they make excellent companions.


Zebra Danio Care Sheet

Active and friendly, Danios share the same peaceful demeanor as Harlequin Rasboras. Their lively swimming adds excitement to the aquarium.

Endler’s Livebearers

Endler's Livebearers Care Sheet

Endler’s Livebearers are small, colorful fish that coexist peacefully with Harlequin Rasboras, creating a vibrant and harmonious community.


Guppy Care Sheet

Guppies’ beautiful colors and calm nature make them ideal tank mates for Harlequin Rasboras, as they both enjoy similar water conditions.


Molly Fish Care Sheet

With their peaceful disposition and diverse colors, Mollies add a touch of elegance to the tank while getting along well with Harlequin Rasboras.

Neon Tetras

Neon Tetra Care Sheet

Both Harlequin Rasboras and Neon Tetras prefer dimly lit environments, making them a perfect match for a serene and beautiful aquarium.


Platy care sheet

Platies’ playful behavior and variety of colors create a lively atmosphere, complementing the peaceful nature of Harlequin Rasboras.

Rummynose Tetras

Rummy Nose Tetras Care Sheet

Rummynose Tetras’ striking red noses and schooling behavior add visual interest to the tank, enhancing the Rasboras’ school.


Swordtails Care Sheet

Swordtails’ graceful looks and easy-going personality  make them compatible companions for Harlequin Rasboras.

White Cloud Mountain Minnows

Peaceful and hardy, White Cloud Mountain Minnows coexist nicely with Harlequin Rasboras, creating a dynamic community.

Cardinal Tetras

Cardinal Tetra Care Sheet

Like Neon Tetras, Cardinal Tetras thrive in similar water conditions and showcase stunning red and blue colors, creating a striking visual contrast with Harlequin Rasboras.

(If you’re looking for some more of the best community fish to choose from, here are over 50 of the best choices!)

Harlequin Rasboras Tank Mates

Harlequin Rasboras Plants

Now we’ll go through some of the best plants you can add to your Harlequin Rasboras’ tank and why they’re perfect for your tank.

Java Fern

Java Fern is an excellent choice as it offers broad, sturdy leaves that serve as great hiding spots and resting places for Harlequin Rasboras. Moreover, they’re easy to care for and can thrive in various water conditions.

Java Fern Bare Root | Microsorum Pteropus – Low Light Freshwater Aquarium Plant
  • Provide natural resting and hiding places for your smaller fish and invertebrates


Anubias is another hardy plant that Harlequin Rasboras will appreciate. Its broad, dark green leaves provide both shelter and grazing opportunities for the fish. Additionally, it’s suitable for low-light setups, making it a versatile option.

SubstrateSource Anubias Live Aquarium Plants – Potted Freshwater Plant for Fish Tanks, Terrariums – Beginner Friendly Low Light (Nana, 1 Pot)
  • Anubias Nana is one of the most popular aquatic plants loved by both beginners and experts alike, and will instantly give your aquarium, paludarium, or terrarium a lush and natural appearance.

Amazon Sword

The Amazon Sword plant is a beautiful and larger option that creates a lush backdrop in the aquarium. Its long, sword-shaped leaves give your Harlequin Rasboras plenty of space to explore and swim around.

Potted Amazon Sword Plant – Beginner Tropical Live Aquarium Freshwater Plant
  • Easy live aquarium plant specie for any freshwater aquarium

Java Moss

Java Moss is a favorite among many fishkeepers for its versatility and easy maintenance. It forms dense, bushy mats that serve as excellent hiding places and even potential spawning sites for Harlequin Rasboras.

Marcus Fish Tanks – 3X Java Moss Taxiphyllum Barbieri – Live Aquarium Plants Moss Aquatic Plants Vesicularia Dubyana
  • LIVE AQUARIUM PLANT – 3 Java Moss (Taxiphyllum Barbieri) golf ball size portion or larger, we like to be generous

Water Wisteria

Water Wisteria is a fast-growing plant that will quickly fill in the aquarium, providing shade and shelter for Harlequin Rasboras. Its delicate, feathery leaves add a touch of elegance to the tank.

Planterest – Water Wisteria Hygrophila Difformis Bunch Live Aquarium Plant Decorations BUY2GET1FREE
  • LIVE AQUARIUM PLANT – 1 Bundle of Water Wisteria (Hygtophila Difformis)

Harlequin Rasboras Breeding

Harlequin Rasboras can be challenging fish to breed, but with a little patience, you can raise a small school of fry.

Here are the steps on how to breed Harlequin Rasboras.

Setting Up a Breeding Tank

The breeding tank should be at least 10 gallons in size and have a soft substrate, such as sand or fine gravel. You should also add some plants to the tank, such as Java moss or Hornwort.

Conditioning the Fish

Before you start breeding your Harlequin Rasboras, you will need to condition them. This means feeding them a high-quality diet and raising the water temperature to 78-80 degrees Fahrenheit.

Adding a Spawning Mop

A spawning mop is a piece of mesh or cloth that can be attached to the side of the tank. The female Harlequin Rasboras will lay their eggs on the spawning mop, where the eggs will be protected from the other fish in the tank.

Removing the Male Fish

Once the female Harlequin Rasboras have laid their eggs, you should remove the male fish from the tank. This is because the male fish may eat the eggs.

Monitoring the Eggs

The eggs will hatch in 2-3 days. Once the eggs have hatched, the fry will be free-swimming and you can start feeding them.

Feeding the Fry

The fry should be fed a diet of microworms, brine shrimp, or crushed flake food. You should feed the fry several times a day until they’re large enough to be moved to a community tank. 

Harlequin Rasboras Common Diseases 

Here are some of the most common diseases Harlequin Rasboras get and what you can do to treat them.

DiseaseSymptoms or CausesSuggested Action or Treatment
IchWhite spots on body and fins, flashing behaviorTreat with medication containing formalin or malachite green
Velvet DiseaseYellow or grayish film on body, loss of appetiteTreat with copper-based medication
Fin RotDeterioration or fraying of fins, redness or inflammationImprove water quality, treat with antibiotics if severe
DropsySwollen abdomen, protruding scalesIsolate infected fish, treat with antibiotics
ColumnarisCotton-like growth on body or fins, ulcers or soresImprove water quality, treat with antibiotics or antifungals
Fish floating at the surface or sinking to the bottomAdjust feeding habits, provide a balanced diet

How Many Harlequin Rasboras Can You Keep Together?

It’s generally recommended to keep 8 to 10 Harlequin Rasboras in your aquarium. These friendly fish enjoy being in a group and get along well with each other. Having 8 to 10 Rasboras in the tank makes them feel safe and happy. 

Also, keeping your Harlequin Rasboras in a group also helps them feel less stressed and stay healthy. So, consider having 8 to 10 Harlequin Rasboras in your tank and see how they interact with each other.

Facts About Harlequin Rasboras 

Let’s go through some of the most interesting things about Harlequin Rasboras that’ll surely make you love them even more!

  1. Harlequin Rasboras are native to Southeast Asia, where they’re found in slow-moving rivers and streams.
  1. Harlequin Rasboras are named after the vibrant black triangular patch behind their gills, just like the diamond pattern of a harlequin’s costume.
  1. Harlequin Rasboras enjoy dim lighting in their tank, mimicking their natural habitat in shaded streams and forested areas.
  2. Female Harlequin Rasboras lay tiny eggs on fine-leaved plants, which can be challenging to spot without close observation.
  1. During breeding, male Harlequin Rasboras show off their colors and dance to impress females.
  1. Harlequin Rasboras are sexually dimorphic, meaning that the males and females can be distinguished by their appearance. The males are more brightly colored and have longer fins than the females.


Here are some frequently asked questions that people have about caring for harlequin rasboras!

Do Harlequin Rasboras Need Live Plants?

Harlequin Rasboras will do fine in a tank without live plants, but they’ll appreciate the cover and hiding places that live plants provide. So, it’s always best to have some live plants in your Harlequin Rasboras’ tank.

Do Harlequin Rasboras Like Bloodworms?

Bloodworms are a high-protein food that Harlequin Rasboras will readily eat. You can feed your Harlequin Rasboras bloodworms as a treat or as part of their regular diet.

Can You Keep 2 Harlequin Rasboras?

You should not keep only 2 Harlequin Rasboras. Harlequin Rasboras are shoaling fish, which means that they prefer to live in groups of 8-10.  If you only keep 2 Harlequin Rasboras, they will be lonely and stressed.

Do Harlequin Rasboras Jump Out Of The Tank?

Harlequin Rasboras are not known to jump out of the tank. However, if they feel threatened or stressed, they may jump. So, if you are keeping Harlequin Rasboras in a tank with a lid, It’s important to make sure that the lid is secure.


Caring for Harlequin Rasboras is a truly rewarding experience. Their peaceful nature, vibrant colors, and captivating behavior make them a joy to have in any aquarium. By providing them with a suitable environment, a balanced diet, and the right tankmates, you’ll see them thrive in your tank!

About the author

Hey! I'm Antonio!

Betta fish keeper for over 6 years now! Since owning a betta I've also housed all kinds of tropical fish, and have seen all manner of problems and how to look after them!

If you need any advice you can always message me or better yet join the Facebook group where a community can answer your questions!

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