Chili Rasbora (Boraras brigittae)

Chili Rasbora is a tiny, bright red nano fish best suited for calm, heavily planted aquariums. It is peaceful and shy by nature, and it becomes noticeably more confident and colorful when kept in a larger group. This species is ideal for nano “nature” or blackwater-style tanks with gentle flow, stable conditions, and plenty of hiding structure (moss, fine plants, wood). Because it is very small, it can be easily stressed by boisterous tankmates, strong currents, and sudden changes in water quality. A mature, cycled aquarium is important, since small fish are sensitive to ammonia and nitrite spikes. They do best with consistent, small water changes and careful feeding (tiny foods only). In the right setup, they show intense red coloration with a darker lateral stripe and active mid-water schooling behavior. They are generally compatible with peaceful nano fish and many shrimp (shrimp fry may still be at risk). Overall, they’re a great choice if your priority is a planted nano display with a calm “micro fish” vibe.

Water parameters

Temperature:	73–81°F (23–27°C), stable and warm.
pH:	4.5-7.0
Hardness:	1–6 dGH (soft water preferred).
Other:	Ammonia and nitrites must be 0 ppm at all times; nitrates should be kept low (ideally under ~20 ppm) through regular maintenance, light feeding, and stable filtration.
Water changes:	Typically change 20–30% weekly to keep water quality stable. In small tanks or with heavier stocking, smaller changes twice per week (e.g., 15–20% twice weekly) can be even better than one larger change.

Behavior & compatibility

Schooling Behavior: Chili rasboras are schooling fish and feel safest in groups; larger groups reduce stress and encourage tighter shoaling. Chili Rasbora (Boraras brigittae) should be kept in groups (minimum 8; ideally 12–15 for best display).
Temperament: Chili Rasboras are peaceful, not aggressive, and not typically fin-nippers. They may be stressed by aggressive or fast tankmates rather than causing issues themselves.
Centrepiece: Chili Rasboras are generally not a single “centerpiece” fish; instead, a larger school becomes the visual feature of the aquarium, creating a colorful focal point through group movement.
Prolific or Livebearing:They are egg-scatterers and not livebearers. They may spawn occasionally in mature planted tanks, but they are not typically prolific in community setups unless breeding is intentionally supported.
Swimming zone:Chili Rasboras primarily occupy the middle to upper water levels and are active mid-water swimmers rather than bottom-dwellers.
Interaction with Plants:Chili Rasboras are excellent with live plants and do not damage them. Dense planting provides security, improves behavior, and can help stabilize water quality in nano aquariums.

Setup essentials

Lid: A tank cover is preferred because they can jump when startled, and a cover also reduces evaporation and helps keep temperature stable.
Filter: A filter is necessary. Use a gentle filter (sponge filter is ideal) because strong flow can stress them, and stable biofiltration is critical for nano fish.
Substrate: Dark, fine substrate (sand or planted soil) is preferred. Dark substrate reduces stress, improves coloration, and works well with planted layouts; optional leaf litter suits blackwater-style tanks.
Lighting: Moderate aquarium lighting is preferred—mainly to support live plants and normal viewing. They don’t require intense light, and floating plants can help diffuse brightness.
Heater: A heater is preferred and can be necessary if room temperature does not reliably keep the aquarium within 23–27°C. Stability is more important than chasing an exact number.
Air Pump: An air pump is not strictly necessary if the filter provides good surface agitation, but gentle aeration is helpful (preferred) in warm tanks, heavily planted setups at night, or if oxygen levels seem low.

Feeding Regimen

Feed 1–2 times per day in small portions. Preferred foods are tiny: micro pellets, crushed flakes, baby brine shrimp, daphnia/cyclops, and microworms. Ensure particles are small enough for their tiny mouths and that all fish get a chance to eat.

Lifespan

With proper care, Chili Rasboras typically live about 3–5 years.

Interesting Facts

They often show their best red coloration in darker, heavily planted or blackwater-style tanks with leaf litter and gentle flow. Larger groups reduce shyness and make their schooling behavior much more visible. Because they’re tiny, they can be outcompeted during feeding—using micro-foods and spreading food across the surface helps ensure everyone eats.