Freshwater Fish

Rasbora Mosquito (Boraras brigittae) – Care Guide

The Rasbora Mosquito (Boraras Brigittae) is also sometimes called Chili rasbora. These brightly colored little fish only grow to be about a half inch long, making them one of the smallest tropical aquarium fish you can buy.

Rasbora Mosquitoes are active yet peaceful little characters, thriving in a community tank of other small, non-aggressive tank mates or in a single species setup when kept in a large school. These lovely nano fish are relatively easy to care for, but they can be very sensitive to water quality, so they ‘re not an ideal choice for a beginner.

In this complete guide, we tell you everything you need to know about caring for the shimmering jewel of swimming called Boraras Brigittae.

Rasbora Mosquito – OVERVIEW

level of care Intermediate
Exercise Active, schooled species
Life expectancy 6 to 8 years
Temper peaceful community fish
tank level Mainly middle to upper areas of the water column.
Minimum tank size 5+ gallons
Temperature range Tropical 68° to 83° Fahrenheit
Hardness of water 1 – 10 dKH
pH range 4.0 to 7.0
Filtration / Flow Rate Prefers well-filtered black water with a low flow rate
Breeding egg layer
Compatibility Peaceful with small and non-aggressive fish species.
OK, for planted tanks? insurance with plants

Boraras Brigittae – ORIGINS

The Rasbora Mosquito was first described in 1978 by Dieter Vogt, who named the fish Rasbora urophthalma brigittae after his wife, Brigitte. The fish’s natural habitat is filled with mosquitoes, hence the creature’s other common name, Mosquito rasbora.

Interestingly, “Boraras” is an anagram of the generic fish name “rasbora”, which refers to the inverted proportion of the caudal and abdominal vertebrae in this genus of fish.

Boraras Brigittae belong to the Actinopterygii class of ray-finned fishes and are characterized by the bony rays that support their fins. Within that class is the order Characiformes, a subgroup of ray-finned fish that contains 17 families, as well as characins. There are six recognized species of rasboras, including the Chili rasbora.

Chili rasbora – NATURAL HABITAT

The Rasbora Mosquito hails from southwestern Borneo and the Indonesian provinces of Central Kalimantan and South Kalimantan.

The fish’s natural habitat consists of blackwater ponds and streams, where the flow is very slow and the peat-stained waters are extremely low in minerals and salts. The pH of the water here can be as low as 4.0.

The water is dark and thin, and fish also enjoy plenty of hiding places and the cover provided by fallen leaves, submerged branches and roots, and aquatic vegetation. The habitat is highly protected and is shaded by overhanging trees and coastal plants.

At the time of writing this report, the Rasbora Mosquito is not listed on the IUCN Red List. However, much of the fish’s natural habitat is rapidly declining, so the species’ future in the wild is by no means assured.


Rasboras peppers may be small, but their bright color makes up for their diminutive size. A school of these fish grouping or darting in the middle of a dense plantation is an impressive sight, making the species a favorite with many hobbyists.

The body of the fish is deep red with a dark stripe and small darker spots at the base of the caudal and anal fins. The edge of the dark striped marking is highlighted by a bright crimson band.

The anal and dorsal fins have dark markings along the anterior perimeter with bright red highlights in males. During the breeding season, male Rasbora Mosquito have intense crimson markings on their tail and pelvic fins.


Chili rasboras are tiny fish, reaching only about a half inch in length at full maturity.


Rasboras peppers have a life expectancy of six to eight years if cared for properly.


Rasbora Mosquitoes are active fish, spending much of their time schooling together in the midwater area of ​​the aquarium. Generally if you keep groups of these fish they will be more confident, whereas if you only have a couple of rasboras they will tend to hide amongst your plants.


The chili rasbora is a peaceful and shy fish, which makes it a good choice for a community setting, as long as you don’t have any very large and aggressive species that might try to make a meal of the little rasboras. Basically, any species that doesn’t try to eat rasboras and enjoys soft, acidic water at a low flow rate is a pretty good bet.

Ideally, choose tank mates that are also small, shy, and non-aggressive. Some good examples of suitable species include neon tetras, minnow catfish, gouramis, dwarf cichlids, lesser cichlids, and other rasboras.

Invertebrates are also a great choice as tank mates for Boraras Brigittae. Dwarf shrimp and aquatic snails can help keep algae down and make an attractive and interesting addition. Check out Cherry Shrimp, Amano Shrimp, and Mystery Snails, which are suitable tankmates for your Rasboras.


If you have a small nano tank, you may want to consider keeping a school of eight to ten Rasbora Mosquitoes. These are naturally schooling fish that should always be kept in larger groups, and make a wonderful sight when kept in a single species setup.


As mentioned above, larger and more aggressive fish such as bettas and angelfish should be avoided. Although they may not harm rasboras, bossy fish will chase and harass their smaller tankmates. That causes stress for both parties, leading to a compromised immune system and potential health problems.


Chili rasboras are fairly straightforward to feed. These fish are essentially omnivorous, meaning they need a diet that contains a mix of plant and vegetable matter and meaty proteins.

The main challenge in feeding your chili rasboras is finding food that is small enough to fit into the fish’s tiny mouths!

WHAT TO FEED YOUR Rasbora Mosquito

So when choosing food for your rasboras, think about what you would give the little fry and go with that. Live foods are a great option, especially small daphnia, small shrimp, micro-worms, wingless fruit flies, vinegar eels, mosquito larvae, and small bloodworms.

Frozen foods are an option if you can’t get live foods. However, you will need to thaw the food and chop or chop it into pieces that are small enough for the rasboras to eat.

Dried fish foods are much easier to feed to your rasboras, although they do not have the same nutritional value as live foods. Be sure to choose a high-quality fish flake or pellet food and grind it to a powder. You can also feed golden pearls, crushed freeze-dried daphnia, and brine shrimp eggs.


To give you an idea of ​​the size of the food you want to feed your Rasboras Mosquito:

  • Feeds in the 100 to 150 micron size range are suitable for small fry.
  • Foods smaller than 500 microns are fine for small adult fish.
  • Foods smaller than 800 microns are fine for full grown fish.


I recommend that you feed your fish twice a day.

Instead of offering your rasboras a large meal, it is better for the fish’s digestion to feed them little and often. So two small meals is the way to go.

If you are not around during the day or night to feed your fish, you may want to consider using an automatic fish feeder with a timer that you can set to deliver a small portion of food at a preset time. These devices are relatively inexpensive and can provide the ideal solution for busy aquarists.


Rasboras peppers are relatively easy to care for, as long as you provide them with the right water conditions.


Due to its small size, the Boraras Brigittae is ideal for small nano tanks. So essentially you can comfortably keep these fish in a 5 gallon tank.

And when you consider that the rule of thumb for fish numbers is one inch of fish per gallon of water, you can see that you can have a school of ten rasboras in a 5 gallon nano aquarium.

However, even though the rasbora is a tiny fish, overcrowding will still cause water quality problems and overload your filtration system. So for that reason, be careful not to put too many fish in your tank.


As with any species of fish, your livestock will thrive if you provide them with an aquarium environment that closely replicates their wild habitat.


A dark colored substrate will really bring out the intense colors of your chili rasboras! These fish do not burrow or feed through the substrate, so fine gravel or sand that mimics the river bottom of the rasbora’s natural environment is a good choice.

The substrate in blackwater habitats usually has a layer of fallen leaves scattered across it, and you can replicate that in your home tank by adding a few handfuls of dried almond leaves. The decomposition leaves leech tannins in the water, turning it the color of tea, and can also help lower the pH of the water, which is perfect for chili rasboras.


Again, to mimic the natural home of rasboras, you’ll need to include plenty of lush plants that the fish can use for cover, along with driftwood, gnarled roots, rocks, and caves.

Leave enough space in the middle of the water column where the fish can swim together.



In the wild, Boraras Brigittae inhabits pools and rivers where water movement is slow or moderate. If your mechanical filter generates too much current, these little fish will have a hard time swimming against the current.

I recommend that you use a simple sponge filter that provides a small amount of movement on the surface of the water. If necessary, use decorations and plants to dampen the flow.


When it comes to water parameters, that is an area that many beginners struggle with when dealing with Chilean rasboras. These fish come from an environment with very specific water conditions. You must closely mimic them in the aquarium so that the rasboras remain healthy and thriving.

water temperature

Chili rasboras are tropical fish that need a water temperature between 68° and 83° Fahrenheit.

pH range and water hardness

The blackwater habitat that is home to the Rasbora Mosquito has extremely soft water that contains very few minerals or salts. So for the fish to stay healthy in the aquarium, the water hardness should be between 1 and 10 dKH, and the pH range should be between 4.0 and 7.0.


The rivers and ponds in which Boraras Brigittae live are in densely forested areas and are shaded by overhanging tree canopy and dense shoreline vegetation.

You can dim the lighting in the aquarium by using floating plants to diffuse the light and provide shelter and cover for the fish. If you prefer, you can choose a lighting unit that allows you to alter the light you have in your tank. If you go that route, there are many beautiful low-light plant species to grow that do very well in low light.


Once you have the water conditions and tank environment set up correctly, Rasbora Mosquitoes are fairly easy to care for. With that said, you should give your fish a clean tank with well-oxygenated water.

The most important thing for rasboras is that the parameters of the water remain stable and constant, since any sudden fluctuation in water chemistry is likely to cause a mass extinction.


Every week, you should use an aquarium vacuum to remove uneaten fish food, fish waste, and decaying plant matter from the substrate and areas where debris tends to collect, such as under decorations, around bases plants and under your box filter if you have one. If you neglect this task, the ammonia produced by decomposing organic waste will make the water toxic to fish.

As part of your general maintenance regimen, you should trim dead plant leaves and excess growth, and refresh dried leaf litter as needed.


In addition to vacuuming the tank, you should do weekly partial water changes of 10% to 15% to keep ammonia, nitrate, and nitrates at acceptable levels. Ideally, there should be no more than 20 ppm nitrate in the water, while ammonia and nitrite should be zero.


Filter cartridges should be replaced periodically according to the manufacturer’s guidelines, and you will also need to rinse the filter media in the tank water to remove sludge that would otherwise prevent the flow of water through the media.


First of all, gather everything you need for your fish tank:

How to set up your aquarium:

  1. Start by rinsing your aquarium substrate under running water to remove loose dust and debris.
  2. Once the water runs clear, you can add the gravel to your aquarium to a depth of two to three inches and sprinkle a couple of handfuls of dried almond leaves across the substrate to create a blackwater environment.
  3. Set up and install your filtration unit and heater, but don’t turn them on yet.
  4. Now, you can fill your tank with unconditioned tap water. In order for your biological filtration system to start the nitrogen cycle, do not condition your tap water. Tap water contains ammonia that the bacteria in the filter media need to start the cycle before introducing the fish.
  5. To avoid displacing gravel all over the bottom of the aquarium, place an upside-down dish on top of the substrate and pour the water over it.
  6. Rinse your tank decorations to remove dust and add them to your aquarium.
  7. Remove dead leaves and broken stems from live plants before planting them in your aquarium. Remember to leave enough space between the samples so that the plants can grow and spread.
  8. Turn on your filtration system and heater, and let the aquarium run for at least ten days before adding your Rasboras Mosquitoes and other animals. I recommend that you test the aquarium water to make sure the ammonia and nitrite levels are at zero before you go out to buy your fish. If you put fish in a tank that isn’t fully cycled, your new pets probably won’t last more than a few days before they succumb to the effects of ammonia poisoning.


Chili rasboras are actually quite hardy fish, as long as you keep the water parameters stable and consistent.


Chili rasboras are generally live fish that love to school in the middle of the tank water or weave in and out of tank plants and decorations.


Warning signs that could indicate health problems may be brewing include:

  • not eat
  • Inactivity
  • Hanging from the surface of the water
  • inflammations and ulcers.
  • Knocking against tank decorations and substrate

Health problem Symptoms or causes suggested action
Ich (white spot disease) Ich is a very common disease in fish that are kept in aquariums. Ich is caused by a protozoan parasite called Ichthyophthirius multifiliis. Ich appears as a sprinkling of white spots on the body, gills, and fins of the fish. Fish rub or rub Ich against decorations and substrate, often breathing rapidly. Raise the water temperature to 82o F for three days and use a white spot disease treatment.
fungal infections White cottony growths. Fish affected by quarantine; dose of water with antifungal treatment.
Bacterial infections Reddened spots on the skin, ulcers. Fish affected by quarantine; dose the water with a patented antibacterial drug.
Columnaris (cottonmouth disease) Columnaris is caused by a gram-negative bacterium (Flavobacterium columnare). Discolored scales, lesions, peeling scales, diffuse spots caused by secondary infections. Fish affected by quarantine; dose the water with a patented antibacterial drug.


Rasbora Mosquitoes are very easy to breed in the home tank as they tend to ignore their eggs and do not eat them like some species of fish do. Although you can set up a separate breeding tank, you will very likely end up with some fry in your display aquarium, as long as it is densely planted so that any surviving fry have a place to hide.

If you have a school of eight to ten rasboras, you are likely to have a mix of males and females, and spawning occurs almost constantly once the fish are mature. Once the eggs are laid, they fall to the bottom of the tank and hatch within 36 to 72 hours. After 36 to 48 hours, the fry are free swimming.

Feed the small fry infusoria and commercial fry foods until they are large enough to take small brine shrimp and the like. The fry will be mature enough to reproduce once they reach six months of age.


Chili rasboras are not commonly seen in fish stores, but you can find them online, usually for a couple of dollars per fish.


Rasbora Mosquito: CONCLUSION

I hope you enjoyed our Chili Rasbora Care Guide.

If you successfully keep Boraras Brigittae, tell us all about your setup in the comment box below. And don’t forget to share our article with your fellow hobbyists if you found our guide to keeping these beautiful little fish helpful!

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