Don’t blink fast or you’ll miss these tiny little fish! Chili rasboras are one of the smallest fish available in the aquarium trade, which makes them a very desirable addition to a nano tank. Their size, peaceful behavior, colorful bodies, and schooling habits make the chili rasbora a minimal yet beautiful addition to the aquarium!
Keep reading to find out everything you need to know about chili rasbora care and keeping these small freshwater fish in your own aquarium!
Boraras brigittae is also known as as the chili rasbora or mosquito rasbora; they may also be referred to as micro rasboras in the aquarium trade.
While these fish are referred to as rasboras, they no longer belong to the true genus of Rasbora. In 1978, they were originally described as Rasbora urophthalma brigittae but were later moved to the Boraras genus based on morphological differences. It is also believed that they were referred to as a mosquito rasbora due to the amount of the blood-sucking insects that were present when discovered.
There are only about 6 other species of fish in the Boraras genus with the chili rasbora being the most desirable within the aquarium trade due to color and temperament.
Chili rasboras are native to Asia, more specifically in the southern regions of Borneo, Indonesia; however, their natural populations are poorly studied so their range could be much larger. In those tropical areas, chili rasboras are usually found in freshwater swamps with blackwater-type streams and pools. This water is stained by tannins that have been released from decaying plants, fallen branches, and other detritus. Water conditions are usually very soft and acidic due to this occurrence.
While the chili rasbora has not been listed under any threatened or endangered lists, their natural ecosystems have become polluted by agriculture, increased infrastructure, and other domestic outputs.
What might look like an empty tank at first may actually be filled with chili rasboras! These incredibly tiny fish can be difficult to see and are usually under appreciated due to their size. However, up-close these fish are just as beautiful as some full grown cichlids, if not more.
Chili rasboras are vibrant red-orange fish with a black and red line that runs down their mid-lateral line; even their small fins have tiny orange dots on them! Female chili rasboras will be larger and less colorful than males. Males will usually be a more intense red and will be more territorial than female fish, especially during spawning periods.
Since they are so tiny, it might be difficult to correctly identify these fish. Other members of Boraras resemble the chili rasbora and it can get confusing, so here are a few ways to tell them apart:
Boraras uropthalmoides. These fish are even smaller than the chili rasbora, only reaching a maximum size of 0.6 inches (1.5 cm)! They live in similar swamp ecosystems but come from Thailand instead. The key to differentiating your Boraras uropthalmoides from your Boraras brigittae is by looking at their mid-lateral stripes.
Boraras uropthalmoides and Boraras brigittae are the only two species within the Boraras genus to have stripes down their side; while these lines are usually broken before they reach the caudal fin, Boraras uropthalmoides will have a dark blotch right before the fin. This will look like a sideways exclamation point.
These fish also tend to be a lighter overall color than chili rasboras, and may have either a yellow or light orange line that runs along with their black stripe. If accidentally purchased together, Boraras uropthalmoides will be noticeably shorter than the chili rasboras even despite their small size.
While it might seem like the two species would be compatible in an aquarium setting, we do not recommend keeping them together due to the possibility that they could breed and cause a hybrid fish.
Boraras merah.These fish are a little more easy to correctly identify, but can still be confused with Boraras uropthalmoides and Boraras brigittae if not looked at carefully. They grow to the same size as the chili rasbora at 0.8 inches (2.0 cm) and come from the same blackwater ecosystems in Borneo, Indonesia.
Unlike the other two species, Boraras merah does not have any mid-lateral lines or stripes. Instead, these small fish will usually have a black blotch towards their gills surrounded by red and orange outlines. While the body is a tanish-yellow color, they will also have more noticeable red coloration towards their head.
They may sometimes be advertised as a phoenix rasbora in the aquarium trade. Again, we do not recommend keeping these fish with Boraras uropthalmoides or Boraras brigittae as they might breed and produce hybridized fish.
How big do chili rasboras get?
These fish are ridiculously small for the color that they carry! Chili rasboras only grow to about 0.6-0.8 inches (1.5-2.0 cm), which makes them a great tank mate for other small species of fish and invertebrate that we will discuss later.
How long do chili rasboras live?
Some hobbyists have reported having their school of chili rasbora for close to 8 years. However, there is a lot of things that can quickly go wrong for these fish due to their tiny size, like being sucked up into the filter or being housed with incorrect tank mates. More likely, your chili rasbora will live between 2-4 years with stable water conditions and good filtration.
Chili rasbora tank requirements
Unfortunately, many people think that just because these fish are small they can be put in a small aquarium. This is simply not true.
To give the best chili rasbora care possible, your school of fish will need at least 10 gallons (37.8 L) with a group of at least 8 or more of the same species. They don’t need much water flow, just enough to keep the aquarium well-oxygenated. Despite their size, these schooling fish are pretty active and will need a decent amount of swimming area where they are not being pushed by the water current.
But what if you have an aquarium that is 5 gallons (18.9 L). Could you just put three chili rasboras together instead of a full school? While many hobbyists make beautiful planted aquarium setups featuring chili rasboras, the answer is no. Many times, those hobbyists have several tanks running where they are able to transfer freshwater fish between systems at any given time, which can lead to a lot of confusion and misinformation for the people considering buying their own chili rasboras.
Chili rasboras are pretty forgiving when it comes to water conditions; for the most part, they require the same water conditions as most other freshwater fish. Water temperature should be stable between 68.0-82.0° F (20.0-27.7° C) with pH between 4.0 and 7.0. These fish prefer more soft and acidic water due to all the decaying plants and vegetation usually found in their natural habitats. In order to recreate this in the aquarium, it is best to stock the tank with lots of plants or to use Indian almond leaves.
If you’ve never heard of Indian almond leaves before, make sure to check out our guide explaining all the uses and benefits to using these water-staining leaves here.
While chili rasbora care is pretty easy, this does not mean that tap water can be used as the primary water source for the aquarium. Tap water contains many unknowns, and can introduce a multitude of problems into your tank. One of the biggest problems with using tap water is the probability of it containing phosphates.
Too many phosphates in the aquarium leads to algae in the aquarium, no matter freshwater or saltwater. While plants need phosphate to live, algae can actually uptake the phosphate before the plants can, leading to more algae and more decaying plants (which will also create even more phosphate!).
Tap water can contain heavy metals, including copper, which can affect the health of your fish and the overall health of the aquarium as well. The only way to know what is in tap water for sure is by sending the water out to a lab.
This is why it is much better to use safer water alternatives like distilled water or reverse osmosis (RO) water. These kinds of water have been filtered for unwanted nutrients and heavy metals so that they are not introduced into the aquarium. Even better, this water is relatively inexpensive and can be easily found at grocery or convenience stores, saving you from a big algae headache and dying fish later on.
Are chili rasboras hardy fish?
For the most part, these fish may be small but they are surely resilient for their size. Like other fish, chili rasboras will be sensitive to big water temperature changes as well as any traces of ammonia or nitrite in the tank.
These fish might also take a little longer to get acclimated to your aquarium than other freshwater fish. For the first few days or weeks, your fish may lose some of the intensity in their coloring. This can slowly be fixed by providing a high-quality diet and allowing time for your fish to become comfortable in the aquarium.
One problem unique to chili rasboras (and from my own experience, neon tetras) is that they are very likely to get sucked up into a traditional aquarium filter. While their size is great for a nano tank, they also perfectly fit into the intake of most aquarium filters. It may be worthwhile to install a sponge filter instead of a regular hang on the back filter to help prevent this from happening.
Chili rasbora tank mates
So, a lot can go with these fish because they’re small and peaceful, right? Unfortunately, no. Their minuscule size actually makes them incompatible with a lot of species. In fact, these small peaceful fish usually do best in their own aquarium with lots of plants and a couple of dwarf shrimp, like cherry shrimp or bee shrimp.
However, if you’re looking to keep your chili rasboras with other fish, here are a few suggestions:
Neon tetra. An aquarium classic, the neon tetra is almost just as small and calm as the chili rasbora. These red and blue-striped fish grow to about 1.2 inches (3 cm) and need a little bigger tank. Neon tetras should be kept in groups of at least 6-8 and will need a minimum tank size of 15 gallons (56.8 L) to themselves.
Ember tetra. At first glance, the ember tetra could be a close relative to the chili rasbora with its signature orange body, though the two are not related. Ember tetras can also grow to about 1.2 inches (3 cm) and will need to be kept in groups of at least 6 or more. They will need at least 15 gallons (56.8 L) to themselves as well.
Pygmy cory. One of the funnest bottom-dwellers to have in a nano tank is the pygmy cory! These small and active fish grow to about 1 inch ( 2.5 cm) and can do well in a 10 gallon (38 L) long aquarium as long as there is enough space to openly swim. Pygmy cories will also need to be kept in groups of at least 8 or more.
Both neon and ember tetras have very similar behaviors to that of the chili rasbora and tend to do well together. Pygmy cories are a bit more active than all three species, but usually stick to the middle and lower water column of the tank where they don’t stress out the other fish as much. More active and larger middle and upper water column swimmers will quickly stress out your chili rasbora and should be avoided!
Because these chili rasboras are so small, they’ve also become a favorite to try as a tank mate with a betta fish. This will not work. Betta fish will eat anything that can fit in their mouth, and that includes a chili rasbora.
Do chili rasboras have to school?
The main reason that chili rasboras can’t go into a 5 gallon (18.9 L) tank is because of their need to be part of a school; a small tank simply does not allow for a school of these fish to thrive. These fish tend to be timid even in larger groups, so separating them into even smaller numbers tends to make them hide and get stressed out.
Yes, chili rasboras need to school in order to be the most active and healthy that they can be in an aquarium setting.
Chili rasbora behavior
Despite being small, these fish are actually pretty active swimmers. They stay towards the middle and upper water columns, but may go more towards the bottom of the tank for food.
Chili rasbora diet
Chili rasboras are micro-predators, meaning they get most of their nutritional value from small prey, like insect larvae, worms, and zooplankton floating in the water. They may especially favor and pick at live plants for any microorganisms they can find, but don’t worry, they’re not actually harming any of the plants.
In the aquarium, these fish need high-quality food to keep their colors bright and vibrant. Frozen and live food, like bloodworms, brine shrimp, and infusoria should regularly be offered and varied throughout the week. These fish will also accept more conventional food, like fish flakes and pellets, but these should be high-quality as well.
Remember, your fish can only eat food that it can swallow. It may be required to cut up pieces of food to make it easier for your chili rasbora to eat.
Breeding chili rasboras
Chili rasbora have been successfully bred and raised in the aquarium setting, and may even do so without having to intervene if conditions are especially favorable. Chili rasboras are egg scatterers and don’t provide any parental care, so in order to increase the likelihood of your baby fish surviving, it is usually best to set up a breeding tank that can be monitored and regulated.
Male fish will display noticeably brighter colors and may begin to chase females around the tank when spawning periods are starting. When this happens, the fish should be moved to a separate heavily-planted and dimmed-aquarium; these fish don’t require too much room for spawning, so clean moderately-sized plastic containers may also prove to be successful. An egg crate or other mesh should be used to line the bottom of the container so that fish will not be able to reach the eggs and eat them.
Water parameters should match those in the main tank with the water temperature being towards the higher end of the spectrum. Make sure to slowly acclimate the fish to a higher water temperature as too much of a change can send them into shock.
If successful, the parent fish should be removed from the container once eggs are spotted. The eggs will hatch the next day and will become free-swimming shortly after that; during the first 24 hours or so, they will get all the nutrients they need from an attached yolk. After that, they will need very small food, like microworms.
Water should not be changed until the fry have grown a considerable amount. Remember, the adults are susceptible to sudden water changes and the juveniles are even more so. Once the fish have grown to a considerable size, it will be safe to reintroduce them back into the main display or give them to another hobbyist.
There is always a chance that your fish will spawn by themselves in the tank and the fry will grow on their own; this is especially true if the tank is well-planted.
Chili rasbora care is easy and straightforward. While they’re small, they shouldn’t be kept in too small of a tank as they need to have safety in numbers and room to swim. Their aquarium setup should represent their natural habitat with soft, acidic, tannin-stained water.
These fish are a little more challenging to find tank mates for due to their size, and they shouldn’t be kept with other species of Boraras but can luckily be kept with an assortment of plants and shrimp.
If you have any questions about the chili rasbora or have kept these fish in your own freshwater aquarium, don’t hesitate to leave a comment below!