Chili Rasbora Care Guide (Boraras brigittae)

The Chili Rasbora is one of the smallest and most stunning nano fish in the freshwater hobby — a 3/4-inch fiery red blackwater fish from the peat swamps of Borneo. At Tropical Treasures Wyo in Cheyenne, Wyoming, they're our most-recommended schooling fish for serious nano aquascapes: small enough for a 5-gallon, vibrant enough to anchor a planted display, and peaceful enough to share a tank with shrimp, snails, and other tiny species.

They're also one of the most commonly mis-stocked nano fish. Most "my Chilis are washed out and hiding" complaints trace back to the same three causes: too few fish, no tannins, and tank mates that intimidate them at feeding time. This guide walks you through how to actually keep Chili Rasboras thriving, based on how we keep and ship them.

Ready to add some to your tank? Browse our Chili Rasbora and the rest of our Rasbora collection — every fish quarantined before shipping.

Quick Facts

  • Scientific name: Boraras brigittae
  • Common names: Chili Rasbora, Mosquito Rasbora
  • Origin: Southwest Borneo (peat swamps and slow blackwater streams)
  • Adult size: 0.6–0.8 inch (1.5–2 cm) — among the smallest fish in the hobby
  • Lifespan: 4–6 years with good care
  • Temperament: Peaceful, schooling, slightly shy
  • Care level: Moderate (due to size and water preferences)
  • Minimum tank size: 5 gallons; 10+ gallons strongly preferred for a proper school

Are Chili Rasboras Hard to Keep?

Not difficult — but they're not as forgiving as guppies or community tetras. Chilis come from very soft, acidic, tannin-stained blackwater, and while they tolerate a wider range than that in captivity, they show their best color and behavior when you lean toward those conditions.

The two areas where new keepers go wrong are school size (anything under 10 fish hides constantly and looks washed out) and water (hard alkaline tap water without tannins keeps them muted and stressed). Get those right and Chilis are one of the longest-lived, most rewarding nano fish in the hobby.

Tank Size & Setup

Minimum tank size

  • Small school (10–12 fish): 5 gallons
  • Display school (15–25 fish): 10 gallons
  • Mixed nano community with Chilis as feature fish: 10–20 gallons

Footprint matters more than height. Chilis spend most of their time in the upper-middle water column drifting in loose schools through plants.

Substrate

Dark substrate (black sand, dark gravel, or planted-tank soil) makes their fiery red coloration pop. Light or pale substrate washes them out and they stay in hiding more.

Aquascape

  • Heavy planting is essential. Java moss, Anubias, cryptocoryne, mosses, and stem plants all work. Chilis feel safe enough to display only when there's plenty of cover.
  • Driftwood and Indian almond leaves. Tannins from driftwood and almond leaves drop pH naturally, mimic their native blackwater, and intensify their red color dramatically.
  • Floating plants. Amazon frogbit, red root floaters, or salvinia dim the lighting from above. Chilis feel most secure under floating cover.
  • Tight-fitting lid. They're tiny but capable jumpers — cover any gaps.

Filtration & flow

A sponge filter is ideal. Chilis hate strong current — they evolved in nearly still peat swamps and will exhaust themselves fighting flow. Avoid powerful HOBs unless you baffle the output. For more help, see our aquarium filtration guide.

Heating

Yes — Chilis are tropical and need a heater. A 25–50 watt heater handles a 5–10 gallon tank. Stable warmth around 76–80°F brings out the deepest red coloration.

Water Parameters

Parameter Ideal Range Notes
Temperature 72–82°F (22–28°C) 76–80°F is the sweet spot
pH 5.0–7.0 Soft, acidic preferred — tannins help
GH 1–6 dGH Soft water — they hate hard tap
KH 0–4 dKH Low carbonate hardness
Ammonia 0 ppm Non-negotiable
Nitrite 0 ppm Non-negotiable
Nitrate Under 20 ppm Chilis are sensitive — keep low

If your tap water is hard, dilute with RO water or use Indian almond leaves and driftwood to gradually soften and acidify the tank. Use a quality dechlorinator like Seachem Prime on every water change. We offer free water testing at our Cheyenne store — bring in a sample.

Diet & Feeding

Chilis are micro-predators with tiny mouths. They will completely ignore food too large to swallow and slowly starve in a tank fed normal flakes.

  • Staple: crushed nano flakes and micro-pellets (Hikari Micro Wafers, Bug Bites Micro, Xtreme Nano)
  • Frozen / live (essential): baby brine shrimp, microworms, daphnia, cyclops 2–3× per week — this is what brings out their best red color
  • Powdered fry food like Hikari First Bites is also useful for the smallest individuals

Feed small amounts 2× per day. Crush flakes between your fingers — most Chili problems trace back to underfeeding because food is too big. For more, see our how often to feed your fish guide.

Tank Mates

Chilis are peaceful but timid. They need similarly tiny, gentle tank mates that won't out-compete them at feeding.

Great tank mates

  • Other nano fish — Celestial Pearl Danios, ember tetras, pygmy corydoras, sparkling gouramis
  • Other Boraras species — Phoenix, Exclamation Point, Strawberry Rasboras
  • Otocinclus catfish
  • Neocaridina shrimp (Cherry, Blue Dream, Yellow) — adults are safe
  • Caridina shrimp in stable, well-cycled tanks
  • Mystery and Nerite snails

Avoid

  • Larger or fast-feeding fish — guppies, larger tetras, danios (out-compete Chilis at meals)
  • Bettas in small tanks (Chilis will get nipped or eaten)
  • Any cichlids, even small dwarfs
  • Fin nippers or boisterous fish — serpae tetras, tiger barbs
  • Goldfish, gouramis larger than sparkling, or any predator

Risky but possible

Caridina shrimplets — adult Chilis may eat very small shrimplets. Heavy moss and floating plants give shrimp shelter. See our Neocaridina shrimp care guide.

Male vs. Female: How to Sex Chili Rasboras

Sexing tiny Chilis takes some practice but is doable on adult fish:

  • Males are slimmer, smaller, and develop intense fiery red coloration with a black lateral stripe. They flare and display constantly when courting.
  • Females are slightly larger, rounder in body, with paler reddish-orange coloration and a less defined lateral stripe. Mature females show a visibly fuller belly when conditioned.

For breeding, target a 1:1 to 1:2 male-to-female ratio in a school of 12+.

Breeding Chili Rasboras

Chilis are egg-scatterers and breed readily in a heavily planted blackwater tank — but adults eat eggs and fry, so saving offspring takes effort.

  • Setup: A 10-gallon species tank with Java moss, Indian almond leaves, soft water (pH 6.0–6.5), and dim lighting.
  • Conditioning: Feed live baby brine shrimp daily for 1–2 weeks to bring fish into spawning condition.
  • Spawning: Pairs scatter tiny clear eggs over moss and plants daily once conditioned. Spawning happens in early morning.
  • Egg care: Adults will eat eggs immediately. Use a mesh egg-saver, breeding mop you can move, or a thick mat of Java moss the eggs fall into.
  • Hatching: Eggs hatch in 24–48 hours. Fry are microscopic and need infusoria or vinegar eels for the first 5–7 days before they can eat baby brine shrimp.
  • Growth: Slow — fry take 4–6 months to reach adult coloration.

Common Problems & Diseases

  • Constant hiding / washed out color: almost always too small a school, lack of plant cover, or no tannins. Add more Chilis (10+ minimum), heavy moss and floating plants, plus driftwood or Indian almond leaves.
  • Slow starvation: the most common Chili killer. Their mouths are smaller than a flake — crush food finely or use proper micro-foods.
  • Ich (white spot): common after shipping. Treat with heat (raise to 82°F briefly) and a half-dose ich medication safe for nano fish (Hikari Ich-X at half dose). See our Common Fish Diseases guide.
  • Sudden deaths in new fish: shipping shock or uncycled tank. Drip-acclimate slowly and only add Chilis to a fully cycled tank.
  • Fading color: hard alkaline water and bright lighting wash out their red. Lower pH with botanicals, dim the lights with floating plants.

Tips for Long-Term Success

  • Keep at least 10, ideally 15+. Confidence and color come from numbers — small groups hide and stay pale.
  • Use Indian almond leaves and driftwood. Tannins are the single biggest factor in deep red coloration.
  • Heavily planted, dim tank. Floating plants over a planted base mimics their native habitat.
  • Crush food finely. Most Chili losses are slow starvation from oversized food.
  • Sponge filter or baffled HOB. Avoid heavy current.
  • Buy from a quarantining source. Every Chili we sell at Tropical Treasures Wyo is quarantined in-house — wild-import Chilis often arrive parasite-laden.

Frequently Asked Questions

How many Chili Rasboras should I keep?

At least 10, ideally 15 or more. They're shoaling fish that show their best behavior and color in larger groups — a trait they share with many of the best schooling fish for freshwater aquariums.

Can Chili Rasboras live in a 5-gallon tank?

Yes — a small school of 10–12 fits comfortably in a planted 5-gallon. They do better in 10+ gallons with more swimming room.

Do Chili Rasboras need a heater?

Yes. They prefer 76–80°F. Room-temperature water in most homes is too cold and dulls their colors.

Are Chili Rasboras beginner-friendly?

They're rated moderate due to size and feeding needs, but a beginner with a planted, cycled nano tank can keep them successfully. Just commit to a school of 10+ and crush their food.

Can Chili Rasboras live with shrimp?

Yes — adult Cherry shrimp, Blue Dreams, and other Neocaridina coexist beautifully with Chilis. Very small shrimplets may get eaten but heavy moss usually shelters them.

Can I keep Chili Rasboras with Celestial Pearl Danios?

Yes — they're an excellent pairing. Same water needs, similar size, and they share the lower-mid water column without competition. See our Celestial Pearl Danio care guide.

How big do Chili Rasboras get?

0.6–0.8 inch (1.5–2 cm) — one of the smallest fish in the freshwater hobby.

How long do Chili Rasboras live?

4–6 years in a stable, planted nano tank. They're surprisingly long-lived for such tiny fish.

Why are my Chili Rasboras so pale?

Three common causes: school is too small, water is too hard or too alkaline, or no tannins. Add more Chilis, dilute hard water with RO if needed, and add Indian almond leaves or driftwood.

Shop Chili Rasboras at Tropical Treasures Wyo

Visit us in Cheyenne at 190 S College Dr, or order online — we ship healthy, quarantined nano fish and aquarium supplies nationwide to all 48 states with our 7-day live arrival guarantee.

Shop Chili Rasbora →
Shop the full Rasbora collection →
Shop the full Nano Fish collection →

Shop Everything You Need at Tropical Treasures Wyo

Visit us in person at 190 S College Drive, Suite D, Cheyenne, WY 82007 or call 307-369-1118. We offer free water testing for Cheyenne locals, expert advice for every tank size, and nationwide shipping to all 48 states with a 7-day live arrival guarantee.

Related guides: Celestial Pearl Danio Care Guide · Emerald Dwarf Rasbora Care Guide · How to Set Up Your First Aquarium · Nitrogen Cycle Guide · Common Fish Diseases & Treatments · Neocaridina Shrimp Care Guide

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.