Harlequin Rasboras—This is How You Feed, Tank, Breed The Tiny Fish

By Eddie Waithaka @aquariawise

Harlequin Rasboras—This is How You Feed, Tank, Breed The Tiny Fish

Harlequin rasboras is a small fish native to South East Asia. It is easy to keep hence beginner-friendly and can tolerate a wide range of water chemistry.

This desirable fish is also quite lively and always on the move mostly within a school at the top of the aquarium. They have brilliant colors as well, and a perfect species to spruce fish tanks kept in open areas in homes.

When keeping harlequin rasbora, you’ll note the fish are generally hardy and will adapt to most aquarium conditions, but for best results, add them in soft, slightly acidic water.

They won’t do well if maintained in hard water, especially if you intend to breed them.

Harlequins are also not picky eaters and will accept and thrive on quality flake foods.

Make sure your water is well filtered and maintained regularly to enhance the health of the fish, plus extend their lifespan.

Even so, keep in mind harlequin rasboras are schooling fish and have to be maintained in a group. Ergo, they are not exactly-aggressive and can be added to a community aquarium.

That said, keep reading to find out how to care for harlequin rasbora since they have a couple of specific needs.

We’ll look at tank size and setup, feeding, breeding, tank mates and more.

Harlequin Rasbora Overview

Harlequin rasbora, also called Red rasbora or simply rasbora, is a small fish in the family Cyprinidae and probably the best-known rasbora among freshwater aquarium fish keepers.

The fish is a great choice for small-sized community tanks and where a large school will make your fish tank vivid and vibrant with movement.

Usually, they have beautiful-metallic bodies with variable colors ranging from pale-pink or bright-red to a copper-orange along the top and bottom.

The back halves of the fish have black triangular or hatched-shaped patches with a bluish tint, and will at times have subtle purple highlights in front of the patch. Others may even have a rosy hue, hence the name red rasbora.

Harlequin rasbora are native to South East Asia where they are spread throughout Malaysia, Singapore, Sumatra, and southern Thailand.

In the wild, they inhabit streams and other watercourses characterized by low mineral content but high concentrations of dissolved humic acid mostly from rivers flowing through peat swamp forests.

How Big Do Harlequin Rasbora Get? (Size)

Generally, red rasbora are tiny with adult fish barely reaching 2 inches in length. However, they are much stockier than other fish in the family

Males are said to have a slightly larger and darker body patch than females with the section adjoining the anal fin being more rounded in males.

Even so, depending on the region of origin, the fish may vary marginally in appearance with those from Thailand usually being smaller and slimmer than those from Singapore, Malaysia, and the greater Sunda Island region.

There is also a chance that rasbora bred in captivity, whether released into the wild and recaptured or sold in the pet trade, will tend to be slightly smaller, though most will still stay within an average range of 1.5 to 2 inches.

How Long Do Harlequin Rasbora Live? (Lifespan)

The average lifespan of harlequin rasbora is anywhere between 5 and 8 years, though most rasbora when kept in aquariums, live for either 5 or 6 years.

However, the lifespan of the fish has not been systematically determined, but individuals kept in the fish tank have almost always lived for the average period (stated above) as long as they are properly maintained and cared for.

Purple Harlequin Rasbora

Purple harlequin rasbora, sometimes referred to as black harlequin is a rare color variant of the fish which displays a purple hue and a black surface.

The color displayed depend on the light reflecting off the fish’s body.

The purple or black harlequin is mostly a captive bred variant, though a few individuals occur in the wilds of Borneo.

Fortunately, the breed gets along with other species same way normal harlequin rasbora do hence can be kept in a community aquarium. Plus the purple-black color gets better as the fish ages meaning you can have it sprucing your tank for a long time.

Black rasbora generally grow to about 1.25 to 1.5 inches, and their average lifespan is 7 years, almost same as the ordinary harlequin.

How Do You Care for Harlequin Rasbora?

Normally, to maintain your harlequin in healthy condition, you need to maintain them in a proper tank and feed them the right diet.

This includes the right size aquarium, good water quality and feeding them quality omnivorous fish food.

Harlequin Rasbora Tank—Size and Setup

Selecting an aquarium large enough to accommodate your harlequin rasboras should not be a hassle as the fish only attain a maximum size of 2 inches.

Even so, they do require sufficient swimming area and also need to be kept in a group.

Overall, any tank that is 10-gallons or more should adequately house your rasboras even when in an ideal group of six individuals.

However, taking into account the tank mates and decorations, it also recommended to keep a group of between 8 and 10 in a tank that is anywhere from 20 to 30 gallons.

More importantly, harlequins should be kept in a long aquarium of 36 inches or more to allow them to swim freely. A cover is also crucial to keep the fish from jumping out of the aquarium.

An aquarium intended to hold rasboras should also be planted with live plants, but have open areas around the middle and top tank areas.

Cryptocoryne species are particularly suitable because they form part of the vegetation in the native harlequin environment. Likewise, other Asian aquarium plant species like Aponogeton and bushy plants like Cabomba can also be used in the fish tank.

Using driftwood is a good way to mimic the natural habitat of the fish, and also use other decorations like large rocks.

Concentrate the plants and decorations near the back and sides your aquarium, such that there are plenty of open swimming spaces left in the middle.

Water Chemistry (Quality)

Harlequin rasbora is a fairly hardy schooling species and will spend much of their time in the open water of the middle and upper regions of the tank. Plus they can adapt to a wide range of water conditions.

Nonetheless, the fish prefer soft aquarium water with a ph range from 6.0 to 8.0, though the water chemistry (as mentioned) is not too restricting as long as the tank cleanliness is maintained.

Use an aquarium filter to keep your tank’s water quality stable. Ideally, go for a filter that provides both mechanical and chemical filtration to ensure adequate removal of both solid and dissolved waste.

A heater installation is also quite important to maintain the water temperature between 72°F and 82°F considering harlequin rasbora are tropical fish and won’t survive in water with the temperature below 70°F.

Always remember to do at least 25 to 50 water replacement once every month or 10 percent changes every week. However, if your tank is heavily stocked, 20 to 25 percent of the water should be replaced weekly or every other week.

Plus you should vacuum your substrate during water changes to make sure no waste is accumulating inside gravel pockets.

The substrate you use should also be at least 1 inch of dark sand or gravel to allow your harlequin rasbora show their best coloration.

Still, diffuse your aquarium lighting by adding floating plants in such a way you simulate the fish wild-environment, but get enough light to bring out the fish color.

That being said, in the wild, harlequin rasbora are used to water with a high concentration of humic acid as they inhabit streams with decayed leaf litter.

Therefore, a useful hack to replicate these conditions is to add dried leaf litter to your tank, which should lower the ph akin to that of black water environments that are stained and acidic.

Lastly, test your water chemistry once a week using an aquarium test kit and record the results in a journal to keep tabs of the normal level for your fish tank.

What Do Harlequin Rasboras Eat?

Harlequin rasboras are omnivores that feed on small insects, worms, crustaceans and zooplankton in the wild.

When kept in an aquarium, they are generally not fussy feeders, meaning they will feed on almost all fish feeds.

To keep your rasbora healthy, feed them a varied diet of high-quality flake food or granules coupled with occasional servings of small live foods like daphnia and artemia.

You may also want to supplement the diet with freeze dried bloodworms or tubifex and fresh vegetables. Some blanched lettuce or spinach are the best greens to feed harlequin rasbora.

The fish d best when fed several times a day, but only what they can eat in less than 3 minutes. However, if you decide to feed them only once a day, provide food they the fish will eat in about 5 minutes.

Feed your harlequin with floating pellets because they are top to middle dwelling fish that rarely swim to the bottom of the tank to swim. Plus always be keen to remove any leftover food from the water to keep the quality safe for the fish.

What Fish are Compatible with Harlequin Rasbora?

Harlequin rasboras are generally peaceful and good community fish, though they are too a bit too active, and an overwhelming personality.

Since they are shoaling fish, they must be kept in a group. Besides, keeping a large school is not only good for the fish well being but also creates a spectacle in an aquarium.

If you choose to maintain them in a community tank, go with other similarly sized and peaceful fish, especially those that prefer comparable water chemistry.

Overall, good harlequin rasboras include other small rasboras, corydoras catfish, Otocinclus catfish, and assorted small barbs.

Cyprinids are also largely acceptable companions as well as characins like tetras, and livebearers like mollies, guppies, platies, and swordtails.

Because harlequin rasboras are top and middle dwelling fish, they are less bothered by bottom-dwellers, therefore you should also consider keeping them with peaceful catfish and loaches as well.

Aquarium fish species that are overly large and aggressive are mostly not good harlequin companions, so I would not recommend maintaining them with cichlids, even though dwarf cichlids are fairly good companions.

Harlequin Rasboras and Betta

Finding good tankmates for betta, especially male, can be challenging and mostly involves more than just keeping them with tropical species that like similar water chemistry.

Betta are especially aggressive to other brightly colored fish or large and threatening fish. Plus they will almost always react to the slightest nip from tank mates.

For this reason, a harlequin rasbora and betta pairing is one of the few options there is to consider.

The two species co-exist together in the wild, so right off the bat, they are going to enjoy the same water parameters in an aquarium. Moreover, their food and dietary requirements are largely similar.

When keeping harlequin with betta, maintain them in a tank with the water temperature anywhere between 72°F and 87°F and a ph of 6 to 7.5.

Even so, you will require a bigger fish tank than you would when keeping harlequin singly. Ideally, a15-gallon tank should be the barest minimum.

Overall, betta fish are generally not a problem for the harlequin rasbora albeit both having brilliant colors because the small fish are too swift for a betta to keep up.

Rasbora also have slim bodies which further makes it easier for them to escape aggressive betta.

Breeding Harlequin Rasbora

It is possible to breed harlequin rasbora in an aquarium, though they are a challenging species. They differ from other rasboras as they are egg layers as opposed to egg scatterers and must have a planted tank to breed.

You’ll also need to keep the tank in clean. Match the conditions to those in the wild and especially maintain the temperature at around 80°F.

Feed your breeding pair with nutritious food rich in proteins such as daphnia and bloodworms to encourage spawning. Mosquito larvae are also a good option.

Intrestingly, it is possible to breed groups of young harlequins in a single aquarium. So you don’t have to set up more than one breeding tank as you would with some with other common fish like betta.

To create an environment akin to fish’s natural setting in your breeding tank, filter your aquarium water over peat to replicate the humic acid concentration in the wild.

Also ensure the water is not hardness is not higher than 4 dH and the ph is around 6.4.

Add cryptocoryne or single-broad-leaved plants like anubias nana in your breeding tank to provide your fish with a place to lay their eggs.

Usually, harlequin rasbora prefer to start spawning in the morning, so place the breeding pair in the tank late in the evening, so that they are ready for the following day.

The Breeding Process

The first sign of spawning in harlequin rasbora is mostly displayed by the male fish which dance and trembles before the female. This is meant to lure her under a suitable plant where she will deposit her eggs.

When the lady is ready to spawn, she will turn upside down and rub her belly against the underside of the leaf where the male fish will then join her and fertilize the eggs as they are released.

Once the parents are done with spawning, separate them from the eggs and fry as they will try to eat them.

The eggs will mostly remain attached to the leaf and take about 18 hours to hatch.

New fry will also remain on the leaf for a further 12 to 24 hours, all this while absorbing the yolk sac. Eventually, the fry will set out from the leaf and become free swimming.

Baby harlequin rasbora should be started on infusoria for a period of 7 to 14 days after which the fry can feed on brine shrimp.

In conclusion, keep harlequin rasbora when you desire unique shoaling behavior and strong colors in your aquarium, with larger groups having a better aesthetic value.

However, if you are also looking to breed them, be aware you will need to give them more attention than you generally would when you don’t intend to breed them.

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