Chili Rasbora (Mosquito Rasbora) – Care, Feeding, Breeding Guide

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The mosquito rasbora, or the boraras brigittae, is a freshwater fish that is a beautiful species if you want to liven up your aquarium. It has an orange body with a blue or black stripe covering most of its body, and it also has some black spots on its fins.

The boraras brigittae is a perfect fish if you want to have a peaceful fish that fits a small sized aquarium, or larger sizes too. It is quite small – when fully grown, it reaches sizes from1 inch to 1.5 inches.

It is a popular fish for many tank owners, because it is peaceful, beautiful and easily fits smaller tank sizes. It is at its happiest when they are put together with other mosquito rasboras.


Dwarf Mosquito / Chili Rasbora (sourceCC BY-SA 4.0)

There are some specifics about this fish that every owner needs to know about. There are many parameters and specifications that you need to keep in mind when you want to keep this fish, but it is the same with any fish.

You want to keep your rasbora happy in order to keep them healthy and maintain longevity.

In this article, we will take a look at every possible aspect about keeping the mosquito rasbora. Consider it a complete guide to owning this beautiful species. We will cover everything from its specifications, feeding, breeding and care tips.

Natural Habitat of Mosquito Rasbora

The mosquito rasbora is endemic to South East Asia, and particularly to Borneo – especially the southwestern part of it, but they can be found all over Indonesia too. Specifically, the species is known to be located in the port town of Bandjarmasin, a town that is located in the Indonesian province of Kalimantan Selatan.

The chili rasbora can be found in rivers in that area, especially black water streams and other swamps and pools that are dark or dim. The conditions of these sort of streams and swamps is very specific. The water is dark there, because of the degrading organic materials that fall into the stream, like leaves, twigs and branches.

The water there is acidic due to these decomposing materials – the ph of the water is sometimes below 5.0, maybe reaching even as low as 4.0. The water is dark and dimly lit due to the thick forest above the water and due to the decomposing organic material.

These sort of environments can be found all across the Southeastern Asia, and are often under threat nowadays due to palm oil plantations.

If you want to keep a mosquito rasbora, you may want to replicate these conditions as closely as possible to make them feel at home more and help them adapt easier.

Fish Tank Requirements

Due to its size, the mosquito rasbora is perfect for small aquariums. It can only grow to about an inch and a half, so you can keep it in a 5-gallon tank easily. You may keep them in larger tanks – 10-gallon or more in a community of fish, but make sure that those fish are also small and peaceful.

Ideally you want to have these fish in a tank setting alone, but that is not a rigid requirement, as these fish can make good tank mates.

The chili rasbora prefers a darker environment with dim water, low light. You may want to have dark substrate in your tank – fine-sized gravel will do best.

The mosquito rasboras are schooling fish and so they prefer to swim somewhere in the middle of the tank. They also prefer to live in densely vegetated environment with plenty of plants and vegetation, as they like to swim around it a lot and hide amongst the vegetation.

Make sure that you put plenty of branches and roots as well as other live plants to make sure that the water will be dim and to make the environment dense.

All in all, the rasboras are small fish mostly suitable for smaller tank sizes.

Water Conditions

Mosquito Rasbora (sourceCC BY-SA 4.0)

The mosquito rasboras will strive under specific water conditions. They prefer soft water with a general hardness of 1 to 2 degrees. This means that the water will have to be slightly acidic.

Try to always maintain the PH levels at 5.0 or below. You will need to test the alkalinity of the water on a regular basis if you will want to keep it at the right level.

While it is ideal and recommended to keep those levels of alkalinity and hardness, it is not 100% necessary to keep it at those levels, as the rasboras can be very adaptive fish and will adapt to higher PH levels and water hardness. Consider using distilled water to create these conditions.

How do you lower the ph of the water in a natural way? Firstly, use distilled water to dilute the tap water. Then you will want to use peat moss or peat pellets or something similar (almond leaves will do the trick as well) – these materials will make sure that the water will be dimly lit, because they will decompose and release tannins, which will make the water darker.

Also remember to keep the water clean at all times, regularly perform maintenance checks, cycle the water often and try to keep the alkalinity in check. Also make sure that the water remains dim.

These conditions will keep the rasboras healthy and it will reduce the likelihood of diseases and bacteria spreading.

Water Temperature

The mosquito rasbora is a tropical fish, so adjust the conditions accordingly. They can live in different water temperatures with lower or higher temperatures, but you want to keep the temperature stable at all times, independent of the temperature.

Even if you want to keep the rasbora in a nano aquarium, you will require a heater. The water temperature is obviously affected by the room temperature, which is often not stable due to weather changes and air conditioning.

Some people think that a small tank does not need a heater, but you will need one, especially if you have tropical fish like the mosquito rasbora.

If the aquarium water temperature is low and chilled, it can affect your rasbora fish drastically. It is not recommended to have a low temperature, as it will put a lot of stress on the fish and it might affect their health.

You may need to buy a submersible water heater and set it at the temperature that suits the rasbora – from 22 degrees Celsius to anywhere up to 28 degrees Celsius.

On the other hand, you do not want the aquarium water to become too warm. Watch out not to have the tank under direct sunlight when it is hot outside.

Keeping the water temperature at the optimal levels is essential to keep the fish healthy.

Diet and Feeding Schedule

One thing that makes the rasbora a popular fish amongst the fish keepers is the fact that they are not too demanding when it comes to diet and nutrition. It is not a picky eater and will eat most types of foods they will be given.

The only important consideration is to make sure that the food is small enough to fit into the rasbora’s mouth, as they have quite tiny mouths.

In a natural habitat, the mosquito rasbora is a micropredator – it feeds on zooplankton, small insects, crustaceans and worms. So you want to make sure that you provide them with a varied diet and that you do not feed them dried foods only.

As for the dry food, buy some high-quality flakes or pellets that are high in protein and other valuable nutrients. The quality of the food will make sure that the rasboras will remain healthy.

Mix the dried foods with frozen foods or live foods like shrimp, microworms and chopped bloodworms. As for the pellets, buy the sinking pellets as the rasbora fish like to swim in the middle of the aquarium or also near the bottom, so the regular pellets might not reach them.

To sum up, make sure that you buy high-quality foods and feed them regularly – once or twice a day, but do not overfeed.

Tank Mates for the Mosquito Rasbora

When you are considering which tank mates to choose for the mosquito rasbora, you need to know a couple of things about the character of this fish.

Firstly, this species is very peaceful and timid. These characteristics are great, but sometimes they are not suitable for a community aquarium because of their timid nature.

Ideally, the mosquito rasbora should be kept together with other smaller species that are also peaceful and shy. Sparkling gouramis, neon tetras, corydoras and other similar small fish.

Besides these other sorts of fish, they will get along with the dwarf shrimp, which is great news if you want to have shrimp in your tank too.

The mosquito rasbora are schooling fish, which means they will be at their happiest with other mosquito rasboras. You should keep them in a group of 8 to 10 rasboras.

That way the fish will be happy and will also look better, especially the male rasboras.

You should avoid keeping chili rasboras with angelfish, betta fish or other larger or aggressive fish.

To sum up, the mosquito rasboras are peaceful and timid fish that will get along with other peaceful fish in a community tank. The best way to keep the rasbora is in groups of 8 or 10, though.

Breeding Dwarf Rasboras

If you want to breed the mosquito rasbora, then you can do so easily, as they are great for breeding and will do so without any encouragement from you. The females will lay eggs almost daily, but they will not actually take care of the eggs. These will collect at the bottom of the tank, and might then be eaten by the fish.

It is quite easy to tell which of the rasboras are male and which are female. The males will differentiate from the females when they are ready to breed – they develop darker black and red highlights on fins, while also a brighter red coloration overall.

The behavior of the males will also change when they are ready to breed. They will become more territorial and aggressive towards other males in order to impress the females.

If you wish to breed some mosquito boraras on your own, you might want to collect the eggs that are scattered on the bottom of the tank. These eggs will be left unattended as the boraras will have little interest in actually developing them.

After you have collected some eggs, you will want to separate them from the other fish in the tank and put it in a separate container the second day after the eggs have been laid.

This fry that you will separate from the original tank will need to be looked after. You will have to feed it live food, like infusoria or some smaller live foods, until they will be able to take larger foods.

Do Mosquito Rasboras Need a Filter?

As previously discussed, the chili rasboras are very small and fragile fish. They prefer to swim in slow moving waters and cannot withstand stronger currents due to their size. In their natural habitat, they swim in slower moving waters with plenty of vegetation and branches that will slow the current down.

Obviously you will want to use some sort of filtration for your aquarium to keep it as clean as possible. Keeping the specifics of the fish in mind, do not purchase filters that are too strong for the fish.

If the filter current is too strong, the fish will not be able to swim freely and might get blown away by the current, putting them in danger of being sucked into the filter, too.

Using plenty of branches, roots and vegetation in your tank is going to be very helpful to create a weaker stream. These obstacles will slow the current of the filter down and will make sure that the current is not too strong for the chili rasboras.

Some filters come available with nozzles that will break up the current of the filter to make it more similar to a river current. This can be helpful to create a more stream-like environment that the rasboras love so much.

Making sure that the rasboras feel at home in your tank is essential, but do not compromise on the filter quality.

Do Mosquito Rasboras Need a Heater?

The rasboras are tropical fish, and you need to keep that in mind when you are setting up your aquarium for the mosquito rasboras. They prefer to live in slightly warmer waters – tropical waters with temperatures of around 22 to 28 degrees Celsius.

Requiring a heater for your tank is going to depend on where your tank will be positioned. If you will have your tank in a room with room temperature, then you will probably need a heater for your aquarium. If your room temperature will constantly float around 23, 24 or 25 degrees Celsius, then getting a heater might not be necessary for you.

Water temperature is a very important thing when keeping tropical fish. They can be very sensitive, especially if the temperature drops suddenly or if it is too high.

You want to keep the temperature constant and without many big changes – those can harm your fish. To ensure that the temperature is constant, you might want to invest in a good submersible water heater. Also, perform water temperature checks as often as you can.

Do Mosquito Rasboras Need Artificial Lights?

The natural habitat of the mosquito rasboras is a dimly lit water due to decaying plants and thick tree canopy above the water. You will want to recreate that sort of environment in your tank.

That doesn’t mean you cannot buy some good quality LED lights for your tank. If anything, those lights might liven up your tank a bit and bring out the best colors of the fish. You can get a modern LED light with a dimming feature and adjustable lighting level to ensure that the conditions remain appropriate.

The plants, branches and roots will provide enough shades where the fish will be able to hide from the light and will also help to recreate the natural habitat conditions.

Can You Use Tap Water for Water Changes?

Using tap water for filling your aquarium is not recommended. Not only for the mosquito rasbora, but for any fish that you might have in your aquarium. The tap water is actually high on some elements that may be harmful for the fish.

Tap water contains some disinfectants to prevent diseases and make it consumable for people. These disinfectants, like chlorine and chloramine, can be very harmful for the fish.

Another concerning thing for aquariums that are softer is that tap water contains plenty of heavy metals, like copper. This chemical can harm your water life if the concentration is too high.

To avoid having too much chlorine and chloramine and also too many heavy metals, you might need to use some water conditioners or dechlorinators to make sure that the water is free of those chemicals

Also, use distilled water or reverse osmosis to mix it with the tap water – this will reduce the amount of chlorine in the water.

To avoid having too much copper in your water, firstly let the water run through the faucet before you use the water, as that can reduce the copper amount by quite a lot.

Then once you have your water ready for cycling, use a small amount of a high-quality water conditioner. This will get rid of a small amount of copper from the tap water.


The mosquito rasbora is a tropical fish that is very popular for many reasons. It is a gentle, peaceful and timid fish that will make your aquarium a joy to watch.

They will get along great with each other or with other peaceful small fish and shrimp. They are the perfect fish for small aquariums, as they are easy to care for, not demanding in terms of diet and they have a good temperament.

Make sure that the tank is properly set and maintained and take care of the fish and you will be rewarded handsomely.

Featured Image:  WikipediaCC BY-SA 4.0

Author Image Fabian
I’m Fabian, aquarium fish breeder and founder of this website. I’ve been keeping fish, since I was a kid. On this blog, I share a lot of information about the aquarium hobby and various fish species that I like. Please leave a comment if you have any question.
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