Chili Rasbora Guide: The Jewel Of Low Light Aquariums

Are you looking to add some color to a low light aquarium?

The Chili Rasbora could be just what you need.

These small but colorful fish are very aptly named – they look just like little spots of chili swimming in the water.

They are one of the many colorful Rasbora that you can add to your tropical freshwater aquarium.

Does your tropical tank have a spot for this beautiful Borneo native?

Keep reading to learn everything you need to know about this fish including what to feed them, habitat and tank setup, their ideal tank mates and much more…

Chili Rasbora Guide The Jewel Of Low Light Aquariums Cover

Chili Rasbora Overview

The Chili Rasbora, Boraras brigittae, is a micro sized minnow from Southeast Asia.

They are native to the western regions of Borneo.

As a member of the Cyprinidae family they are related to some of the most popular aquarium fish including Goldfish and Koi carps.

This fish was first discovered in the early 1990s and was originally known as the Rasbora brigittae.

Because of their size (less than an inch in length) they are classified as a Nano fish.

Since these fish are only found in one part of the world not very much is known about their population dynamics in the wild.

Most of what we know about this fish comes from the aquarium trade.

A Chili will usually live from 4 to 8 years in the right tank conditions.

You are most likely to find this uncommon specimen at an online retailer rather than a pet shop. Prices typically range from $2.99-$4.99 for a school of 10 fish.

The Chili Rasbora is a wonderful introduction to the world of nano tanks but they are not for those who are new to fishkeeping in general. Their highly specific tank conditions and inability to tolerate water fluctuations makes them better for aquarists who already have some tropical freshwater fish experience.

Key Facts:

  • Experience Required: Freshwater fishkeeping and Nano aquariums.
  • Nicknames: Mosquito Rasbora.
  • Color Forms: Scarlet red or deep orange with black lateral lines.
  • Size: 0.70-0.78 inches.
  • Tank Size: Minimum 5+ gallon.
  • Tank Temperature: 77°F to 82°F.

Pros and Cons

Pros

  • Great for brightening low light aquariums.
  • Does not need a large tank.
  • Tolerates moderate to high acidity.
  • Suitable for Nano tanks.
  • Blend nicely in planted tanks.
Cons

  • Must be kept in a school of 7 or more.
  • Can not tolerate shifts in water quality.
  • Very anxious around larger fish.
  • Difficult to find a quality supplier.

Chili Rasbora Appearance

A Chili Rasbora

The Chili Rasbora is one of the tiniest Nano fishes around and only reaches 0.70-0.78 inches.

However what it lacks in size it makes up for in beauty.

Their bright colors and shimmering lateral lines are a wonder to behold. They come in any shade from red to deep orange, with black lateral lines that can be solid or split. Chilis have a single dorsal fin, homocercal caudal fin, pelvic fin, and anal fin. All four of these fins will have patches of red and black.

They are shaped like a torpedo and have a very streamlined swimming pattern.

Males are more brightly colored than females and the intensity of their color increases when they are looking for mates. You will notice the females have a duller and more faded coloration.

You can tell the males and the females apart by looking at the color and shape of the fish.

Males have very intense red colors from blood red to scarlet to cherry. Their bodies are thinner, more streamlined and they are shaped like bullets. Females on the other hand look faded and are often mistaken for the Phoenix Rasbora and other lighter colored fish. They are larger in size, rounder in shape and their colors range from cherry red to sunset orange.

During courtship the males turn a brighter color to attract a mate and the females’ abdomens will round out in preparation for carrying eggs.

Common Color Varieties

The Chili Rasbora comes in two different color varieties:

Red and black: This is the most common color variety. You can expect striking red scales in shades from blood to cherry red, with shimmering black lateral lines that can be split or solid. All four fins have patches that match the color of the scales.

Orange and black: This color variety only occurs in females. Expect deep orange scales with the same shimmering black lateral lines as the red and black variety. This variety is often mistaken for the Phoenix Rasbora.

7 Fun Facts About Chili Rasboras

  1. The species is only found in Western Borneo, near Indonesia.
  2. This elusive little fish was first discovered in the wild by Maurice Kottelat in 1991. He published his findings in his paper Freshwater Fishes of Western Indonesia and Sulawesi in 1996.
  3. Their scientific name, Boraras brigittae, is the result of an anagram of Rasbora and the name of Kottelat’s wife.
  4. It is one of the many fish that thrive in highly acidic peat bogs. Many other species of nano fish live in these habitats too including the world’s smallest fish, Paedocypris progenetica.
  5. This species is among 5 others that are grouped into the Boraras genus – the Phoenix Rasbora and the Pygmy Rasbora are two others that are quite popular.
  6. Chilis and other fish in the Boraras genus have an anatomy unique from the Rasbora. Boraras have more vertebrae near the caudal fin than the abdomen – it is the opposite in Rasbora.
  7. They are classified as a micro predator and feed on microscopic live prey.

Habitat and Tank Conditions

Mosquito Rasbora

Chili Rasbora are native to the tropical peat bogs of Borneo.

They are found in small pools alongside slow flowing streams and creeks. In this habitat underwater plants block out the light and provide shelter and security for the fish. This secretive little minnow prefers this low light habitat where they can easily hide from predators.

Dead and decaying plant material will also make the water acidic, which your Chilis will appreciate.

In this wild environment the substrate is covered with sphagnum moss which creates even more acidity.

Darkness, warmth, and acidity are the three rules when setting up a Chili Rasbora tank.

Ideal Tank Set Up

Your tank must be fully cycled before you introduce your Chili Rasbora. This way you know that there will be no sudden changes or fluctuations in your water quality.

The ideal water temperature is 77-82°F and water hardness should be between 1 and 2 dGH. Your water temperature should never dip below 75°F, so a good heater is a must to keep the temperature at tropical levels.

You should use a fine gravel that is heavily enriched with sphagnum moss.

Your tank’s pH should range from 6.0-7.0 or moderately acidic.

You should keep the flow slow to prevent your little fish from getting stressed. A low flow hang on back filter or even a simple sponge filter will work wonders in a tank like this.

One of the most important aspects of a Chili tank is low light.

The lower the light, the happier your fish will be.

If you have other fish that need a brighter light then you can use a moderate intensity aquarium light. However the bottom levels of the tank must be well shaded by plants and other decorations.

Now is the time to utilize all of the best low light plants.

Chili Rasbora will take shelter in plants with wide, thick leaves that can grow along the bottom levels of the tank. Java ferns and crypts are some of the best plants that you can use with Chilis. Java moss and Najas grass also make excellent low light carpets.

You can include driftwood, logs or twigs for a little bit of extra shelter – your fish will appreciate them (especially in a community tank).

Tank Parameter Requirement
Minimum Tank Size 5 Gallons
Tank Type Freshwater planted
Temperature 77-82°F
pH 6.0-7.0
Hardness 1 to 2 dGH
Flow Light
Substrate Fine gravel

What Size Aquarium Do They Need?

You can keep Chili Rasbora in a 5 gallon tank – this species is a nano aquarium favorite.

If you are keeping a community tank then you will need at least a 10 gallon tank.

You can keep 2-4 schools of 8-12 Chili Rasboras in a 20 gallon tank.

Tank Mates

Chili Rasbora In Freshwater Tank

In the wild these fish would be found with other fish in the Boraras and Rasbora genus including the Phoenix and Pygmy Rasbora.

Within an aquarium they can be kept with other peaceful fish that are under 2 inches long.

Anything larger than 2 inches is likely to alarm them and cause stress.

As you might expect the Phoenix and Pygmy Rasbora make the best tank mates.

The Harlequin Rasbora is also a very popular choice as their color compliments the Chili Rasbora’s colors nicely.

Outside of other Rasbora they can be kept with small catfish such as the Corydoras and Dwarf Suckers. Sparkling Gouramis, Micro Glassfish, and Guppies also get along very well with them. Some of the smaller Danios (such as the Zebra and Pearl Danio) make good additions to a community tank with Chilis.

If you are looking for non-fish tank mates then you can include peaceful aquarium shrimp such as: Cherry Shrimp, Amano Shrimp and Ghost Shrimp. You can even include a few Nerite Snails.

Since these fish are very easily scared you should avoid keeping them with large or rambunctious species. Most species of Gourami are just too much for these little guys to handle.

Also avoid any fish with pushy, rowdy or aggressive personalities. Clown Loaches, Bettas and most Barbs make very poor choices. White Clouds and other temperate nano fish are also a bad idea as they will not be able to tolerate a tropical water temperature. Goldfish are also out for the same reason.

Keeping Chili Rasbora Together

These fish must be kept in a school of 7 to 12 individuals.

The larger the school, the happier your fish will be. If your school is too small your fish will be very unhappy and will spend most of their time hiding.

Your Chilis will eagerly interact with one another inside their school but will not pay much attention to others outside of it.

Chili Rasbora Care

Chili Rasbora Swimming

While this fish is not particularly high maintenance they do need very specific water parameters to survive.

Because of this they are not recommended as a beginner friendly fish.

A single species tank is easier for newcomers to maintain.

One of the biggest issues with this fish is their susceptibility to stress and anxiety. Anxiety can lead to shock and ultimately death.

If they are kept in a tank with too many, or too few individuals in a school, then these little guys will become overwhelmed.

Another key part of their care is maintaining the water parameters.

Sudden changes in water quality can also cause problems.

You should disturb Chili Rasbora as little as possible and never cycle your tank while your fish are still in it.

Other than their anxious nature, they are typically very healthy fish. However they are still susceptible to ich and other common illnesses just like any other fish. Check your water parameters and regularly monitor the water quality – especially after cleaning or cycling your tank.

Erratic behavior, uncoordinated swimming, decreased appetite and hiding often are all signs that your Chili are not feeling very well.

Diet

A Mosquito Rasbora

These micro predators feast on the smallest of live prey.

Insect larvae, plankton, tiny shrimp and microworms are all on the menu in their natural habitat.

When keeping them in an aquarium they should be eating the same kind of food. However they will enjoy some pellets and fish flakes alongside their micro prey.

While they are not strictly vegetarians they can snack on a little bit of algae. If you see your fish going after the algae in your tank they are likely going after the microscopic prey hidden in the algae.

Water fleas and brine shrimp are some of the best live prey that you can give your Chili Rasbora.

Though these fish prefer live prey it is ok to supplement their diet with freeze dried microinvertebrates and worms – just make sure that most of their food is given live. Any pellet and flake foods that you get should be slow sinking and small enough to fit into the fish’s mouth. Crushing them into fine powder is the best thing to do.

You should feed them every day, at least twice.

It is best to feed non breeding fish once in the early morning and once after sundown – this will mimic their feeding schedule in the wild.

What Food Can They Eat?

The best foods for Chili Rasbora are:

  • Water fleas
  • Brine shrimp
  • Tubifex worms
  • Bloodworms
  • Cyclops and other copepods
  • Crushed pellet foods
  • Crushed flake foods
  • Freeze dried micro invertebrates
  • Algae (supplement)
  • Plant material (supplement)
  • Paramecium and other protists (larval stage only)

Behavior

These fish should be kept in schools of 7 to 12 individuals and you will notice they are quite social with the others in their school.

When kept in a large school they will be curious but when kept in a small group they will become skittish.

Also when larger fish are nearby they will become much more timid and will keep out of the way most of the time.

The sudden presence of a larger fish may startle them, causing them to freeze up or quickly dart away.

You are most likely to spot them in the dusk to dawn hours (before sunrise and after sunset). In the wild this is when they are most active because it is hard for predators to hunt them during this time. The middle of the tank is the highest level that you will spot these elusive minnows. You can watch them weave in and out of your underwater plants close to the bottom.

When it is time to choose a mate these otherwise calm fish become very rambunctious and even a bit aggressive towards one another.

Males will organize territories to defend from other males. They will flash their bright colors as they charge and rush at the others. You might spot your courting males do some amusing underwater acrobatics while they attempt to impress the females.

Breeding Chili Rasbora

Chili Rasboras Swimming

This fish is very easy to breed.

Any school will have a mix of male and female fish so mating is inevitable. You can expect your fish to spawn many times throughout the year.

When your fish start displaying courtship behavior you will need to feed them more often than usual (up to 4 times a day) to get them into mating and breeding condition.

A males color will become more intense and the females’ abdomens will round out when they are ready to breed.

Your males will attempt to dominate one another and establish small territories to defend.

They will charge at any other male that attempts to intrude on their ground.

Once a female has selected a mate, spawning will occur and she will lay up to 50 eggs over a 2-3 day period.

You can place some Najas grass or Java moss in a breeding tank for the female to lay her eggs on.

Make sure to remove her from the breeding tank once she spawns.

Cover the eggs with leaf litter from your other aquarium plants to give them a little more security while they hatch. The eggs should hatch within 2 days.

You will not need to feed the larvae until they lose their yolk sac – this should take around 2 days.

After that give them powdered flakes and tiny microscopic prey.

The larvae will reach the fry stage within 7 to 10 days and will be able to eat the same kinds of food they will eat as adults (see above).

They will reach full maturity before the end of the first month.

History and First Sighting

Chili Rasboras

This elusive species is a very recent addition to the aquarium hobby.

It was discovered by Maurice Kottelat in 1991 and published 5 years later in his collection of native Southeast Asian fish.

Originally it was included alongside 150 other species in the genus Rasbora. However anatomical differences in this and 5 other species inspired a new genus (Boraras).

Boraras are often known as micro Rasbora due to their smaller size.

Not much else is known about this fish in the wild. Their secretive nature means that it is very rarely seen and it can only be found in just one area of the world.

It is thought they first entered the aquarium hobby in the late 1990s.

Their cousin, the Pygmy Rasbora, has been kept in the aquariums since the 1950s!

To this day the Chili Rasbora is still quite uncommon in aquariums, but it is very well loved by niche hobbyists and nano tank enthusiasts.

Species Summary Table

Chili Rasbora
Other Common Names: Mosquito Rasbora
Scientific Name: Boraras brigittae
Family Name: Cyprinidae
Distribution: Borneo
Size: 0.70-0.78 inches
Color: Red and black, orange and black
Care Level: Moderate
Temperament: Peaceful
Lifespan: 4-8 years
Minimum Tank Size: 5 gallons
Tank Mate Compatibility: Nano fish, small shrimp and snails

Should You Keep The Chili Rasbora? (Summary)

The Chili Rasbora is a truly rewarding task for a Nano aquarium keeper to take on.

Novice fish keepers or those with little experience in Nano fish or tropical tanks will find their care needs a little daunting. They are best for those who already have fishkeeping experience.

The little minnows are colorful and fun to watch.

As long as your water quality is consistent your Chilis will do just fine.

Plenty of other beloved Nano species are compatible with these little fish and you can even use them to bring color to the aquatic areas of a paludarium.

All of these points make the Chili Rasbora a great and versatile addition to all kinds of tropical freshwater tanks.

Do you keep Chilis in your aquarium? Let us know below…

About David Thomas

David Thomas David has been keeping fish since he was a child. In his first tank he kept goldfish and since then he has kept over 30 different species. Now he has 4 separate tanks and his favorite is a 100 gallon freshwater tank with a school of Rasboras, Tetras and Loaches.

Comments

  1. Most sites and sources recommend 10G or 45 cm x 30 cm as lowest size. Here it says only half that is minimum, which is correct? They are said to be active swimmers, I am confused by the information given here,

    Reply

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