Slender rasbora

Rasbora daniconius

Also known as Blackline rasbora, Striped rasbora, Slender barb

FreshwaterFish

Slender rasbora (Rasbora daniconius) — Captain R C Beavan · Public domain

Care at a glance

Temperature: 72–81°F (22–27°C)
pH: 6.0–7.5
Adult size: 3.9 in (10 cm)
Minimum tank: 32 gal (120 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Easy
Breeding: Medium
Rarity: Common
Origin: Widespread across South and Southeast Asia, from Sri Lanka and India to the Mekong basin.
Family: Cyprinidae

Overview

Keep slender rasboras in a group of at least eight in a tank of 120 litres or more, since they are active swimmers that reach around 10 cm. Water at 22 to 27 C with a pH of 6.0 to 7.5 suits them, and a lid is wise as they can jump. Feed flakes, pellets, and frozen or live foods such as daphnia, bloodworm, and mosquito larvae. They are peaceful and make good dither fish for larger community tanks.

In the wild

The slender rasbora lives across a huge range of streams, rivers, ponds, and ditches from Sri Lanka and India into mainland Southeast Asia. It shoals in open midwater and adapts to many conditions. A bold dark stripe edged with gold runs the length of a slim silver body. It is a hardy, active rasbora that grows larger than the common nano species.

Good to know

Rasbora daniconius has carried many common names, including blackline, striped, and golden striped rasbora, reflecting its wide range and long history in the hobby. It reaches about 10 cm in the tank and more in the wild. Its broad distribution means fish from different regions vary in size and exact color.

Did you know

The gold-edged black stripe catches the light as the shoal moves, and in older books this was one of the standard beginner rasboras before the smaller nano species took over.