Chili Rasbora Care: Nano Tank, Group Size and Water
Published: 2026-10-28 · FishyKart Blog
At well under an inch long, the chili rasbora (Boraras brigittae) is one of the few fish that genuinely suits a nano aquarium. Adults reach about 0.6-0.8 inch (1.5-2 cm), come from slow, tea-coloured blackwater streams in southwest Borneo, and look their reddest in a planted tank with soft, slightly acidic water. They need a group of 10 or more and food small enough for their tiny mouths, but in return they ask for very little space.
Photo: Daiju Azuma - Wikimedia Commons, CC BY-SA 4.0
| Parameter | Value |
| Scientific name | Boraras brigittae |
| Origin | Blackwater streams, southwest Borneo |
| Adult size | 0.6-0.8 in (1.5-2 cm) |
| Lifespan | Several years; around 4-5 years commonly reported |
| Group size | 10 or more |
| Temperature | 72-82°F (22-28°C) |
| pH | 5.0-7.0 |
| Minimum tank | 5 gallons tight minimum; about 10-11 gallons recommended |
| Diet | Micro foods: crushed pellets, baby brine shrimp, daphnia |
Small Fish, Small Margin for Error
A tiny tank holds very little water, and every mistake shows up faster. Chili rasboras should only go into a fully cycled tank, and a 10-gallon tank gives you a far bigger buffer than a 5-gallon one when a feeding goes wrong or a heater fails. Use a gentle filter, such as a sponge filter, because strong flow pushes these fish around and can pull them into an unguarded intake.
Getting the Red Colour
Chili rasboras that look pale in the store are usually stressed, not poorly coloured. Their red comes out with dense planting, floating plants to dim the light, a dark substrate and soft water. Leaf litter, such as dried catappa leaves, tints the water brown the way their native streams are. Males are usually redder and slimmer and spar briefly with each other; females are rounder and paler.
Feeding Tiny Mouths
Most flake food is simply too big. Crush flakes or use micro pellets, and offer baby brine shrimp, daphnia or other small frozen foods several times a week. Feed small amounts once or twice a day: in a nano tank, uneaten food fouls the water quickly. The live foods described in our brine shrimp guide are an easy way to bring out colour and condition.
Tank Mates and Plant Choices
Chili rasboras get along with other tiny, peaceful species, such as ember tetras, white cloud minnows at the cooler end of their range, and dwarf shrimp. Skip nippy nano fish such as dwarf pea puffers, which harass fish this small. Anything big enough to swallow a 0.7-inch fish will eventually do so. Easy plants such as java moss, java fern and floating plants make a complete home without CO2 equipment.
Small rasboras for planted tanks are listed as espei rasboras and hengeli rasboras.