Mosquito 'Chili' Rasbora - Boraras Brigittae

Mosquito 'Chili' Rasbora | A Tiny But Fiery Nano Fish for Planted Aquariums

The Mosquito Rasbora, also known as the Chili Rasbora (Boraras brigittae), is one of the most strikingly beautiful nano fish in the freshwater aquarium hobby — and one of the smallest. Native to the peat swamps and blackwater streams of Borneo, Indonesia, this tiny jewel of a fish packs an extraordinary amount of colour into a body barely half an inch long. Males display a vivid, almost neon red body with a bold black lateral stripe edged in red, and intense red fins that glow brilliantly under aquarium lighting. A well-established colony in a lush planted tank is one of the most breathtaking sights in the nano aquarium hobby.

Despite their tiny size, Chili Rasboras are active, confident fish with plenty of personality — darting energetically through plants and open water, displaying to one another, and lighting up any space they inhabit with constant flashes of red.

Mosquito Chili Rasbora Care Guide

Care at a Glance

• Scientific name: Boraras brigittae
• Also known as: Chili Rasbora, Mosquito Rasbora, Brigitte's Rasbora
• Adult size: up to 0.8 inches (2 cm) — males slightly smaller and more intensely coloured than females
• Minimum tank size: 10 gallons — nano tanks of 5–10 gallons work well for a small colony
• Temperature: 75–82°F (24–28°C)
• pH: 4.0–7.0 — soft, acidic blackwater conditions strongly preferred
• Hardness: 1–5 dGH — very soft water essential for best colouration and long term health
• Best kept in groups of 10 or more
• Lifespan: 4–8 years with good care

Chili Rasbora Tank Setup

A blackwater-inspired planted nano tank is the ideal home for Chili Rasboras and will produce the most stunning display of their colouration. Dark substrate, dense planting, floating plants to diffuse light, driftwood, and tannins from Indian almond leaves or botanicals all help replicate their natural peat swamp habitat. The darker and more heavily planted the tank, the more confident and colourful these fish will be. Gentle filtration is essential — a sponge filter is ideal, as any strong flow will stress these tiny fish. They are sensitive to water quality and do best in a mature, well-established aquarium with stable, soft, acidic parameters.

Feeding Your Chili Rasboras

Micropredators in the wild that feed on tiny invertebrates and zooplankton. In the aquarium they accept high quality micro flake and nano pellet foods, but thrive best with regular offerings of appropriately sized live or frozen foods — baby brine shrimp, micro worms, daphnia, and cyclops are all excellent choices and will significantly enhance their colouration and encourage spawning behaviour. Their small mouths mean food size matters — standard flake and pellet food should be crushed finely before feeding.

How Many Chili Rasboras Should You Keep?

Groups of 10 or more produce the most natural behaviour and the most impressive colour display. In a well-planted tank with a large colony, males will display constantly to one another and to females — fanning their fins, intensifying their colouration, and competing for the best positions in the group. The result is a constantly shifting cloud of red that is one of the highlights of the nano aquarium hobby.

Chili Rasbora Tank Mates

Due to their tiny size, tank mate selection is critical for Chili Rasboras — anything with a mouth large enough to swallow them is a potential predator.

• Other nano fish such as Ember Tetras, Green Neon Tetras, and small Danios
• Pygmy Corydoras and other micro bottom dwellers
• Dwarf shrimp such as Neocaridina and Caridina — excellent tank mates that share similar water parameter preferences
• Nerite snails and other small snail species
• Avoid any fish larger than 1.5 inches that may view them as food
• Avoid boisterous or fast-moving fish that will outcompete them for food and stress them with their activity