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If you are thinking of setting up a nano tank with live aquarium plants, then you have to try chili rasboras or mosquito rasboras. Unlike most red aquarium fish that tend to have a warmer, red-orange hue, these tiny rasboras display a deep, cool-toned red with distinct black markings. However, they often get passed over because the juveniles sold at pet stores are miniscule and look washed-out. Find out what it takes to raise these stunning nano fish so they reach their full adult coloration that will keep you staring at the aquarium for hours.

What are Chili Rasboras?

Boraras brigittae is a close cousin of other micro rasboras, like the exclamation point rasbora and strawberry rasbora. They only grow to about ¾ inch (2 cm) long and have a slender body with pointed fins. While the adults are known for their intensely scarlet scales, they will temporarily become paler whenever they move from one tank to another. Just give them a couple of weeks to adjust to their new environment, and their true colors will show again. Also, most nano fish are very timid because of their fear of predators, but in our experience, chili rasboras are refreshingly bold by comparison. No, they won’t rush to the front of the tank to greet you, but if you stay still for a few seconds, they often approach the glass out of curiosity.

Chili rasboras are known for their vibrant red bodies with a black, horizontal stripe.

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How to Set Up an Aquarium for Chili Rasboras

Chili rasbora are found in the rainforests of Borneo and Indonesia, where tons of trees block out the sunlight and plant leaves often fall into the water, breaking down into brown tannins. This means they come from acidic, softer waters, but in our experience, chili rasboras are quite hardy and can handle a much wider range of water parameters. We have successfully kept them in pH levels of 6.0–8.0, temperatures between 72–82°F (22–28°C), and soft to hard water. To recreate the dim lighting of the jungle, use plenty of low light plants that create shady areas and good hiding spots for both the adults and fry. Our favorites include java fern, anubias, cryptocoryne plants, dwarf aquarium lily, and floating water sprite. For a biotope tank that imitates their natural setting, try adding some dried catappa leaves to tint the water, gently lower the pH, and create biofilm for the fish to nibble on.

Because of their petite size, mosquito rasboras have a very low bioload and produce little waste, so we have successfully kept them in planted fish tanks as small as 3 gallons. They are not the fastest swimmers, so aim for a filter with low current like a sponge filter. If you use a hang-on-back or canister filter, make sure to cover the filter’s intake tube with a prefilter sponge so the nano fish won’t accidentally get sucked up.

How many chili rasboras should be kept together? As a schooling fish, getting a larger group of chili rasboras will help them feel more comfortable and confident about swimming out in the open. Their small, slender bodies can be harder to notice unless you have a lot of them, so we like keeping a school of at least 8–12 together.

What fish can live with chili rasboras? Boraras brigittae is a very peaceful species that would do great with other similar-sized community fish that are not big enough to predate on them. Compatible tank mates include lambchop rasboras, rosy loaches, ember tetras, dwarf cory catfish, neon green rasboras, snails, and shrimp. Yes, all fish will try to opportunistically snack on baby shrimp, but chili rasboras won’t bother the adult shrimp.

Chili rasboras get along well with other peaceful nano fish like clown killifish.

What Do Chili Rasboras Eat?

In the wild, they feed on zooplankton, micro worms, insect larvae, and other tiny invertebrates. Therefore, look for fish foods that are small enough to fit in their mouths or are soft enough for them to take bites out of. They prefer to feed from the middle of the water column, so floating or slow-sinking foods should be offered. Also, they are not the most aggressive eaters and can easily be outcompeted during mealtimes unless the food is fine enough to spread everywhere. That being said, chili rasboras are not picky eaters and will eat everything from frozen rotifers and cyclops to Repashy gel food (in its powder form) to live micro worms. To bring out their vivid red coloration, our favorite foods are crushed krill flakes, Easy Fry and Small Fish Food, and baby brine shrimp.

How to Breed Chili Rasboras

Nano fish have nearly microscopic babies, so we have the best luck breeding them in a mature aquarium that has lots of live plants, catappa leaves, and other botanicals that create mulm and microfauna for the fry to constantly graze on. To prevent the adults from predating on their own eggs, cover the bottom of the tank with plastic craft mesh (purchased from a craft store), and put a thick layer of java moss, a yarn spawning mop, Easter basket grass, or other fluffy, dense plants underneath the mesh. The mesh allows the eggs to fall through, but the holes are too small for the adults to enter. Also, acidic pH below 7.0 may help improve the hatch rate and survival of the offspring.

To ensure you have fish of both sexes, get a group of least 6 chili rasboras. Females tend to be rounder and less colorful, while males are smaller and have the brightest reds. Condition the adults for breeding by feeding them plenty of high-quality foods such as live baby brine shrimp. Then place them in the mature, breeding tank for a couple of days and remove them as soon as they’ve spawned or you spot any fry. Feed the babies multiple, small meals a day consisting of fry foods like infusoria and vinegar eels, and in a couple of weeks, they should be large enough to eat live micro worms and baby brine shrimp.

Juvenile chili rasboras are not very colorful at first, but with good care and patience, they will one day look as red as rubies.

While Aquarium Co-Op does not ship live fish, you can visit our preferred online retailers to see their current stocking lists. For more inspiration, check out the top 10 stunning nano fish you need to try in your next small fish tank.