Blackline Rasbora — a Cyprinidae from Mekong basin, SE Asia, peaceful and energetic; shy only when kept too few. Reaches 7.5–11 cm; shoaling; 8–10+ for constant motion and confidence. 22–26 °C.
Care parameters
Water temperature
22–26 °C
pH
6.5–7
GH hardness
5–15 dGH
Adult length
7.5–11 cm
Minimum tank
145 L
Water layer
Bottom-dwelling
Difficulty
Moderate
Temperament
Peaceful and energetic; shy only when kept too few
Origin
Mekong basin, SE Asia
Species overview
From the waters of Mekong basin, SE Asia comes Rasbora borapetensis, a member of the family Cyprinidae. A restless micropredator of the surface film, evolved for open, sunlit water. It lives on the bottom. Adults reach 7.5–11 cm. Shoaling; 8–10+ for constant motion and confidence. Generous swimming room, a big school and clean water cover nearly all of its care. Maintain 22–26 °C at pH 6.5–7. A solid choice for a well-planned community tank.
Native biotope
Habitat
Clear streams and rivers over gravel
Flow
Moderate, well-oxygenated current
Dissolved O₂
Appreciates well-oxygenated water
Aquascape & hardware
Substrate
Fine gravel and sand
Hardscape
Water-worn stones and driftwood
Plants
Hardy rooted plants along the margins
Temperament, diet & tankmates
Schooling
Shoaling; 8–10+ for constant motion and confidence
Diet
Omnivore; accepts everything small enough
Recommended tankmates
Other danios and small rasboras — Form a fast, peaceful upper-water school
Avoid keeping with
Slow, timid fish — Outcompeted at the surface
Breeding & notes
Sexual dimorphism
Males often slimmer and more colourful
Breeding method
Spawns at dawn over fine plants; eggs fall to the bottom