Chili Rasbora Care Guide: Tank Size, Diet & Breeding

Chili Rasboras (Boraras brigittae) are tiny, vibrant, and perfect for nano tanks. But they are not just “easy community fish.” They require specific blackwater parameters, and their first month in your tank is critical. Most wild-caught specimens carry internal parasites that will kill them if you don’t quarantine them. Here is the no-nonsense guide to keeping, feeding, and actually breeding them.

Quick Notes about Chili Rasboras

Description 

• Size. This is a very small freshwater fish. The typical adult size of this species ranges from 6 to 0.8 inches (1.5 to 2 cm) in length.
• Body Shape: The body is slender, elongated, and laterally compressed. The body shape is somewhat streamlined, typical of Rasboras.
• Coloration. The main body coloration is red or pinkish with prominent black stripes along the sides and a slight thickening in the center. This line terminates with a black wedge-shaped spot at the beginning of the caudal fin. A red stripe runs along its upper body, extending to the base of the tail.
  Note: The fish displays muted colors when young. However, its hues become more vibrant around 1 year old.
• Fins. The fins are small, semi-transparent, and may have red and black streaks. There is a small dark spot at the base of the tail. Red spots adorn the caudal fin, while sections of the dorsal and anal fins also display red coloration.

Lifespan of Chili Rasboras

Currently, there is no data available on the maximum lifespan of Boraras brigittae in the wild.

In aquariums, with appropriate conditions, Chili Rasboras can live for around 4 to 8 years.

Typical Behavior 

Temper:

Chili Rasboras are absolutely peaceful fish. They will not bother anybody in the community tank. These fish do not exhibit aggressive behavior to other species of fish.

Although males of this species will compete for dominance with each other and dominant male may even claim some territory for that.

Anyway, despite the existence of hierarchy, all conflicts are usually resolved without causing any harm. Their “Fights” look like this: facing another males head-on or head-to-tail, they begin to “lash out” with their fins and bodies towards each other, intensifying their colors in the process.

They do not nip.

Sociality:

Although Chili Rasboras is a social species, they do not stay in close proximity all the time. Thus, it is not schooling but rather a shoaling fish.

In the aquarium, it is recommended to start with a group of at least 6-8 individuals. Larger groups contribute to their overall happiness and reduce stress levels.

Activity:

Chili Rasboras are moderately active fish. Generally, they do not swim like crazy in aquariums but they can move really swiftly when they choose to.

This small fish is not very skittish. On the contrary, it will swim quite actively even in open areas. Of course, it may need some time to adapt to its surroundings.

Additionally, you may even notice that when first introduced, the fish pales, which is quite normal. Once the stress subsides, its color will return. This process usually takes from a couple of hours to several days.

Interestingly, their jumping ability, particularly when stressed or frightened, is often overlooked in other sources and articles.

Placement in Tank:

Generally, they spend most of their time at the top and middle parts of the tank.

They enjoy exploring their environment and are particularly fond of areas with tall and dense vegetation or places to hide.

Features:

• Social: Yes
• Activity: Moderate
• Placement: Top and middle dwellers
• Peaceful: Yes
• Nippers: No
• Jumpers: Yes

Feeding and Diet

Boraras brigittae is a diurnal omnivore. In nature, these fish feed on microscopic organisms, including insect larvae in densely vegetated areas.

They are not very picky eaters. In the aquarium, Chili Rasboras can be provided with a diverse range of frozen or live foods, including:

• brine shrimp (artemia salina),
• Artemia nauplii,
• daphnia,
• fruit flies,
• rotifers,
• vinegar eels,
• cyclops, etc.

Generally, they will happily consume dry and freeze-dried foods such as flakes, pellets, and crisps as long as it is small enough to fit into their mouth for mastication and digestion. Therefore, large pieces of pills, granules, and flakes food should be crumbled into tiny parts (like powder).

Note: Chili Rasboras go crazy for live baby brine and fluval bug bites! They absolutely love it. It also helps their coloration!

How to feed Chili Rasboras:

This is a diurnal species, so it is better to feed them in the morning.

Ideally, feed them in small portions (at least 2 times a day) rather than a large amount once a day. This mimics their natural feeding behavior and helps prevent overfeeding and digestive issues.

Features:

• Diet Type: Omnivore
• Food Preference: Meat
• Feeding Frequency: Daily

Are Chili Rasboras Plants Safe?

Yes, this species can be kept in planted tanks. They will not eat any healthy plants in the tank. This species does not eat living plant material.

Keeping and Housing 

Before introducing them to your tank, it is important to create optimal environment for them. Therefore, ensure your tank is properly cycled. Regularly test water using a kit to monitor ideal conditions.

Tank size:

Chili Rasboras are small fish and do not require a lot of volume. They can be easily housed even in a 5-gallon (20-liter) nano-tank.

Ideally, a 10-gallon tank (40 liters) is the sweet spot. You can safely stock 15 to 20 Chili Rasboras in a 10-gallon tank. For a 5-gallon nano tank, keep the school to 6-8 fish maximum.

In larger tanks, they will be ‘lost’ and difficult to see. However, the challenge with nano tanks is maintaining stable water parameters, which can be quite difficult for beginners.

Therefore, unless you are already an experienced aquarist, I would recommend staying away from small setups.

Water parameters:

Chili Rasboras inhabit blackwaters in the wild. This discoloration is primarily due to the presence of tannins and other organic compounds leaching into the water from decaying plant matter, such as leaves, branches, peat, etc.

That is why these fish clearly prefer biotopes with very soft water and acidic conditions.

Note: To create the effect of tropical “blackwater,” we can use, for example, Tetra ToruMin solution with natural peat extract.

Temperature: Ideally, Chili Rasboras need water temperatures ranging between 72 to 82°F (22 to 28°C). They tolerate cooler temperatures (up to 68°F or 20°C) in winter if acclimated slowly.

pH: The ideal pH range is between 5.0 – 7.0. In their natural environment, they thrive in acidic waters.

Hardness: The tank should preferably have soft to medium water hardness as well. Therefore, anything in the range of 1 – 8 GH is acceptable. They do not like very hard water.
Note: Although they can adapt even to harder water, eventually, it will reduce their lifespan.

Lighting:

Chili Rasboras does not like bright light, it makes them stressed. These fish enjoy subdued lighting.

Therefore, if you are creating an aquarium specifically for this species, you should consider only plants that can thrive in low lighting conditions, as well as floating plants, which will help create dim lighting in the aquarium.

Related articles:

• Top 10 Low Light Aquarium Plants. Pros and Cons
• Top 7 Floating Plants for Beginners
• Advanced Guide to Planted Tank Lighting

Water flow:

In the natural ecosystem, Chili Rasboras inhabit shallow waters where the current is absent or very slow-moving. They are not strong swimmers.

Therefore, stagnant water or very slow water currents are recommended for tanks housing this species.

Filtration:

Filtration will be crucial as it partly affects the water flow in the aquarium. Therefore, it is recommended to choose filters with minimal flow, such as sponge filtration.

Substrate:

No special requirements.

In planted tanks you can use an active substrate, besides boosting plants’ growth rate it will also help you to maintain a low pH level in the water.

Decorations:

Chili Rasboras lives in its natural habitat, which is characterized by an abundance of driftwood, leaf litter, and vegetation. They like to hide darting in and out of cover.

This should be replicated in an aquarium.

Plants provide good hiding spots as well. You can use floating plants, fake plants, driftwood, leaves, and rocks to provide great hiding spots for them.

Related article:

• Do We Need Tank Decoration? Simple Ideas

Acclimation:

Before putting Chili Rasboras into the tank, you need to acclimate them properly.

Do not rush the process!  

Be very careful during the acclimation process and use the drip method. Sudden changes in habitat can harm them.

Related article:

• How I Drip Acclimate Shrimp and Why (the process for acclimating the fish is the same).

Problems Associated with Chili Rasboras

Despite being very small fish, Chili Rasboras are quite resilient and hardy. Usually, there are no problems with them except during the first month!

The thing is, most of these fish sold are captured in the wild. As a result, they undergo stress from prolonged transportation, and there is also a risk that they may be infected with something. All of this manifests in the first month, which is the most challenging.

Internal parasites

They start to develop sunken stomachs and become noticeably thinner. They seem to lose their energy, hiding away and showing signs of apathy. Strangely, their coloration often remains normal, and their scales are in perfect condition.

Treatment: Use Metronidazol – 1g/100liters and do water changes 40% for the next 2 days.

Columnaris

Columnaris is a bacterial infection that affects fish, often appearing as white, fuzzy patches on their skin, fins, or mouth (mold-like lesions). It’s highly contagious and can spread rapidly throughout the tank, particularly in stressed or weakened fish.

Treatment: Use Seachem Kanaplex for 1 week. Do 30-40% water changes at the 3^rd and 5^th day.

Ich

Ich is a common parasitic infection that affects freshwater aquarium fish. It appears as tiny white spots, resembling grains of salt, on the fish’s body, fins, and gills. It is highly contagious.

Treatment: Increase the temperature of the aquarium to around 82-86°F (28-30°C). Higher temperatures accelerate the life cycle of the Ich parasite, making it more susceptible to treatment. Dose Ich-X, using 5 ml of medication per 10 gallons of aquarium water, and allow 24 hours for the treatment to take effect. Do water change and dose again.

Important: Quarantine Infected Fish. Remove it from the main tank and place them in a separate quarantine tank to prevent the spread of deseases.

Related article:

• How To Setup an Easy Quarantine Tank

Common Mistakes When Keeping Chili Rasboras

Critical: The First Month

Most Chili Rasboras are wild-caught. They have endured long shipping and often carry internal parasites. The first month is the most dangerous. Quarantine all new fish. If you skip this step, expect losses. This is not a myth; it is the reality of keeping this species.Treat prophylactically with Metronidazole (1g/100L).

Breeding 

Let me be upfront: breeding Chili Rasboras in captivity is difficult. The scientific literature on their reproductive behavior is practically nonexistent. Most “guides” online copy from each other. The reality is that successful breeding is rare, and most reported cases are accidental.

Here is what is actually known:

• They become sexually mature at the age of 8-10 months.
• Sexual dimorphism is weak. Females are slightly larger and having a rounder belly. Males have more vivid coloration compared to females.
• Borarasbrigittae is an egg-scattering spawner.
• These fish are daily spawners. Females lay only 2-3 eggs each day.
• Parents do not care (guard)for their eggs and/or fry.
• Egg incubation last from 24 to 48 hours.
• After hatching, fry rely on the egg sack as a nutritional reserve in the first days of life.
• After 4-5 days, the fry already start attempting to swim, and adopt a horizontal position. From this point on, the fry spend most of their time swimming and often hide among plants. At this stage, they are almost entirely transparent.
• After 5-7 days they can eat microworms, vinegar eels, rotifers, and brine shrimp.
• They become more or less similar to adults after 1.5-2 months, although they usually attain their full coloration only by their first year of life.

The Hard Truth About Breeding
The main challenge is that they spawn daily in small numbers, not in a single large batch. Removing adults after spawning is nearly impossible because they do not spawn synchronously. You would need to remove them daily, which stresses the fish and defeats the purpose.

Most successful breeding in home aquariums happens by accident in heavily planted, mature tanks where fry can hide among dense vegetation and leaf litter. The survival rate is low. If you want to increase your chances, you need:

1. A dedicated spawning tank(5-10 gallons, no substrate, dim light, pH 5.0-6.5, GH 1-6, temp 79-82°F (26 – 28°C)).
2. Spawning mop or protective neton the bottom to catch eggs.
3. Conditioned parentsfed live food (cyclops, baby brine shrimp) for 2-3 weeks.
4. Remove adults after 2-3 days(they will have produced some eggs). Donotexpect a largebatch.
5. Fry food:Infusoria, vinegar eels, or rotifers for the first 5-7 days.

Expectation management: Even with perfect setup, you will not get consistent results. This is not a beginner breeding project. If you get a few survivors, consider it a success.

Suitable Tank Mates

This is a very friendly fish that is suitable even for nano tanks. 

When choosing tankmates for Chili Rasboras, it is important to consider their size and behavior. They cannot compete with other species and might be targeted for bullying.

Fish:

You can keep this fish with other peaceful fish of similar size. You won’t achieve success if you keep them with larger or aggressive fish; they will spend all their time hiding among plants.

Ideally, you need to choose species that prefer (or can tolerate) soft and slightly acidic aquarium water, such as:

• Least Killifish,
• Pencilfish,
• Harlequin Rasboras,
• Pygmy Cory,
• Dwarf sparkling gouramis,
• Otocinclus Catfish,
• Galaxy Rasboras, etc.

Shrimp:

Chili Rasboras and dwarf shrimp – compatible or not? The short answer is yes, but with conditions.

Safe for adult shrimp.
Chili Rasboras will not harm adult or juvenile dwarf shrimp that are a couple of weeks old. They inhabit the upper and middle layers of the tank, so they rarely interact with substrate-dwelling shrimp. In community tanks, shrimp populations continue to increase despite the presence of Chili Rasboras.

Risk to baby shrimplets.
Chili Rasboras are opportunistic micro-predators. They will eat newly hatched shrimp fry if they find them. Shrimplets are tiny, slow-moving, and easy prey. If you are breeding expensive shrimp (e.g., Caridina or high-grade Neocaridina), keep the fish in a separate tank.

If you are keeping cull-grade shrimp or a low-cost colony, Chili Rasboras are fine.

Tip: Heavily planted tanks with dense moss (Java Moss, Christmas Moss) provide hiding spots for shrimplets. This increases survival rates even with fish present.

Snails:

Chili Rasboras is compatible with any freshwater snail. They do not eat or harass them.

Avoid:

• Large and/or aggressive, and/or boisterous fishes.
• Keep them away from all types of crayfish and most types of freshwater crabs. 
• Even small African Dwarf Frogs can and will try to catch them whenever possible.

Related article:

• Can You Keep Crayfish With Other Fish?
• Aquarium Crabs and Tankmates. Possible or Not?

Taxonomy

In 1978, German ichthyologist and aquarist Dieter Vogt (1927 – 2020) described this fish as Rasbora urophthalma brigittae. Nowadays the correct name is Boraras brigittae.

Kingdom: Animalia (Animals)
Phylum: Chordata (Vertebrates)
Class: Actinopterygii (Ray-finned fishes)
Order: Cypriniformes (Carps, minnows)
Family: Cyprinidae (Carp family)
Genus: Boraras (Small fish)
Species: B. brigittae

The findings show that Boraras species belong to a single evolutionary lineage, which is identified by 4 distinct characteristics:

1. they don’t have a particular type of canal near their eye,
2. their urohyal bone has a unique shape,
3. their fourth rib on the side of their body is elongated, and
4. a specific bone called the postcleithrum is attached high up on another bone called the cleithrum.

Etymology

This genus name “Boraras” is an Indian word for a fish, also used in Malay peninsula. Additionally,  “Boraras” is an anagram of the generic name “Rasbora,” symbolizing the reversed ratio of abdominal and caudal vertebrae unique to this genus.

This species was named “Brigittae” in honor of Dieter Vogt’s wife, Brigittae.

Distribution

Boraras brigittae is endemic to Indonesia (from West Kalimantan and some parts of Central Kalimantan). Its range extends from southwestern Borneo to the Jelai Bila river basin near the town of Sukamara.

Habitat 

In their natural habitat, Chili Rasboras usually occur in tranquil stagnant pools, ditches, swamps, and slow-flowing streams.

Typically, they inhabit areas with muddy substrate and dense vegetation. The water often takes on a dark brown hue due to tannins and other substances released during the decomposition of organic matter such as fallen leaves, branches, and driftwood.

References:

1. Conway, Kevin W. “Monophyly of the genus Boraras (Teleostei: Cyprinidae).” Ichthyological Exploration of Freshwaters16, no. 3 (2005): 249.
2. Körner, H.-J., 2010- BSSW-Report 22(2): 21-28 Boraras merah ist doch ein Synonym von Boraras brigittae!
3. Liao, T. Y., Kullander, S. O. and F. Fang, 2009- Zoologica Scripta 39(2): 155-176 Phylogenetic analysis of the genus Rasbora (Teleostei: Cyprinidae).