Black Line Rasbora Care Guide
Rasbora borapetensis · Freshwater Fish
What Black Line Rasbora look like
The Black Line Rasbora (Rasbora borapetensis) exhibits a slender, fusiform body that typically reaches a maximum adult size of approximately 2 inches (5 cm). Its morphology is characterized by a strikingly distinct dark lateral line that extends from the operculum to the base of the caudal fin, providing a stark contrast against its silvery body. The caudal fin is notably forked, with the lobes adorned with vibrant red-orange tips, which serve as a visual cue for potential mates and rivals. Sexual dimorphism is subtle; males tend to display more vivid coloration, particularly in the tail, while females may appear slightly fuller-bodied when gravid. Defensive adaptations include a schooling behavior that enhances safety in numbers, and the species lacks specialized spines or venomous structures, relying instead on its agility to evade predators.
Behavior & temperament
The Black Line Rasbora is a social fish that thrives in groups, exhibiting a strong tendency to form schools within the mid to upper water column of their aquatic habitat. They are primarily pelagic, often found swimming in open water, but may also venture near the surface in search of food. Breeding behavior is characterized by egg scattering, where females release eggs among dense vegetation, providing some cover from predation. The species is generally peaceful and non-aggressive, making it an ideal candidate for community tanks, although males may display mild territoriality during breeding periods.
Diet & feeding
In the wild, the Black Line Rasbora is an omnivore, feeding on a varied diet that includes small invertebrates, zooplankton, and plant matter. In captivity, they require a balanced diet consisting of high-quality flake food, supplemented with live or frozen foods such as daphnia and brine shrimp to ensure optimal health and coloration.
Behind the name
Rasbora (from the Malay word 'rasborah', meaning 'to swim in schools'); borapetensis (referring to the region of Borapet in Thailand, where the species is commonly found).
Plan your tank
Check the numbers before you buy: tank volume, a stocking plan, cycle progress, water changes, and your ongoing care routine.
Keeping Black Line Rasbora?
AquaLens identifies your fish and plants from a photo, tracks water chemistry, and flags health issues early — free on iOS and Android.
