Chili rasboras (Boraras brigittae), also called mosquito rasboras, are tiny red schooling fish with very small mouths. Their care depends less on buying elaborate equipment than on providing stable water, gentle filtration, enough companions, and food they can actually eat.
For most home fishkeepers, we recommend a mature, planted 10-gallon aquarium or larger with a group of at least 8–12. Smaller specialist setups exist, but a 10-gallon tank gives more room for a group and more margin for routine maintenance.
Chili rasbora care at a glance
| Care factor | Practical guidance |
|---|---|
| Scientific name | Boraras brigittae |
| Adult size | About 3/4 inch |
| Group size | At least 8–12 of the same species |
| Recommended starting tank | 10 gallons or larger, established and planted |
| Temperature | 74–80°F is a useful everyday target |
| Water preference | Soft, acidic to neutral water; ask about the supplier’s conditions |
| Filter | Gentle flow; protect exposed intakes |
| Food | Fine complete food plus suitably tiny live or frozen foods |
| Temperament | Peaceful; vulnerable to predators and food competition |
Identification and natural habitat
Chili rasboras originate from southwestern Borneo, where they inhabit shaded freshwater habitats associated with peat-swamp forests. They were described by Vogt in 1978; claims that they were first discovered in 1991 are incorrect.
Look for a slender body with red coloration and a dark lateral marking. Males are often more intensely colored, while mature females may look fuller. Color alone is not enough to identify every fish: related Boraras species are sometimes mixed or mislabeled in the trade. Ask the seller for the scientific name rather than relying only on “dwarf rasbora.”
The Seriously Fish species account discusses their distribution and similar-looking species. Their forest habitat explains the preference for shelter and subdued light, but a home aquarium does not need to reproduce every extreme wild-water measurement.
Tank size and group size
Use a group-based stocking plan, not a fixed number of fish per gallon. Tank dimensions, filtration, plants, feeding, and other inhabitants all affect the result. Start with one group and watch water quality before adding more animals.
A species-focused 10-gallon setup is easier to plan than a crowded miniature community. If you want other schooling fish or bottom dwellers, choose a larger aquarium so each species can have its own suitable group. A lone chili rasbora or a pair does not replace a school.
Setting up a stable planted aquarium
- Establish the filter first. Do not use these fish to cycle a brand-new tank. Confirm that the system can process waste before stocking it.
- Provide shelter. Arrange plants at different heights, with shaded spaces and small open areas for feeding.
- Protect the intake. A sponge filter is one option; cover a power filter’s intake with a suitable prefilter sponge and check it for clogging.
- Keep flow gentle. Fish should be able to hover and feed without being swept across the aquarium.
- Control temperature. Use a thermometer and, where needed, a thermostatic heater. Avoid direct sun as a heating method.
Begin with plants that fit the available light and maintenance routine rather than adding equipment simply because a tank is planted. Our low-light aquarium plant guide can help you compare planting options. Leave access to the filter, heater, and substrate for maintenance.
Water parameters: stability before extreme numbers
A practical planning range is around pH 6.0–7.0 and 1–10 dGH, approximately 18–179 ppm general hardness. These are not sharp survival boundaries. Aquarium Co-Op reports keeping chili rasboras in a broader range, while species references emphasize their soft-water origins. The source and acclimation history of your fish matter.
Test your tap water before buying. If it is much harder or more alkaline than the supplier’s water, discuss a sustainable plan with an experienced fishkeeper. Do not suddenly force an established tank to a lower pH with chemicals. GH measures general hardness; KH describes buffering capacity. They are different tests, and deliberately driving KH to zero can make management more difficult.
Use dechlorinated replacement water with reasonably matched temperature and chemistry. For a lightly stocked tank, a modest weekly partial water change is a useful starting routine; adjust its size and frequency using tests and the amount of waste. Small fish still need maintenance.
Ammonia and nitrite should read 0 ppm. Test promptly if fish gasp, stop eating, or act unusually, and correct a water-quality problem before assuming an infection. This aquarium water-testing guide explains the different readings. Keep records so you can recognize changes rather than relying on a single result.
Feeding tiny mouths successfully
Choose a complete food fine enough for the fish to swallow. Finely crushed tropical flakes or an appropriately sized micro food can form the staple, with small live or frozen foods providing variety. Suitable options include baby brine shrimp, microworms, or tiny frozen cyclops; check particle size rather than assuming any package marked “small fish” will work.
Offer small portions once or twice daily and watch individual fish take food. Spread it over a sheltered feeding area so the whole group gets access. Food drifting past the fish or accumulating below them is a sign to adjust its size, quantity, or delivery—not simply add more.
If other fish take every meal first, change the feeding arrangement or separate incompatible competitors. A planted tank may support tiny natural food organisms, but it should not be assumed to feed an adult group without supplemental food.
Choosing tank mates
Chili rasboras are safest with similarly small, peaceful animals that thrive in the same conditions. In a sufficiently large aquarium, carefully selected small tetras or dwarf catfish may be options. Account for the tank mates’ group sizes and activity levels as well as their adult lengths.
Avoid fish large enough to swallow them, persistent chasers, and fast feeders that prevent them eating. Bettas vary individually, so this is not a dependable beginner pairing. A calm-looking large fish can still regard a chili rasbora as food.
Adult dwarf shrimp can be compatible, although tiny shrimplets may be eaten. Check the shrimp’s water needs separately; very soft, acidic conditions do not suit every shrimp or snail. See our freshwater shrimp guide before planning a mixed setup.
Breeding chili rasboras
These fish scatter eggs and do not guard their offspring. A mature, densely planted tank may produce occasional fry, but adults can eat eggs and young. For a planned attempt, prepare a separate stable setup with gentle filtration, fine vegetation or a spawning mop, and a way to keep adults away from eggs.
Prepare microscopic fry food cultures before spawning. Feed only once fry are free-swimming and ready to eat; newly hatched fry initially rely on their yolk reserves. Larger foods can be introduced as their mouths develop. Raising fry successfully is more demanding than simply seeing eggs, so avoid relying on a promised egg count or rigid day-by-day schedule.
Common problems and buying checklist
Why are my chili rasboras pale?
Juvenile coloration, transport, lighting, and stress can all affect appearance. Look at appetite, breathing, fins, and behavior alongside color. A pale fish is not automatically sick, and a bright fish is not proof that water is safe.
Are chili rasboras beginner fish?
They can suit a prepared beginner with an established aquarium, but are a poor choice for an uncycled bowl or an unstable first setup. Tiny food and close observation are important.
How long do they live?
Plan for several years of care. Published hobby estimates vary, so a precise average or guaranteed maximum would be misleading. Purchase healthy fish and maintain consistent care rather than treating a lifespan figure as a promise.
Before buying, confirm the species, group size, supplier’s water conditions, and foods being accepted. Quarantine arrivals separately before adding them to an established community. Do not add medication solely because the fish are small or newly purchased; persistent symptoms need an appropriate diagnosis, ideally with an aquatic veterinarian’s help.
