All fish / Lebiasinidae

One-lined Pencilfish

Nannostomus unifasciatus

Also known as oneline pencilfish, one line pencilfish, one-banded pencilfish, one lined pencil fish, single stripe pencilfish, onestripe pencilfish, ワンラインペンシル, ナノストムス・ユニファスキアータス, 一线铅笔鱼, 斜线铅笔

This is a slim pencilfish that swims at an oblique, head-up angle, with a single bold black stripe running from the snout into the lower lobe of the tail. Males have a rounded tail with red and white markings. It is kept for its unusual posture and calm nature in planted blackwater set-ups.

Care at a glance

Care level

Moderate

Temperament

Peaceful

Adult size

5 cm

Temperature

24 to 28 °C

pH

5 to 7

Smallest tank

60 litres

Keep as

Group of 8 or more

Diet

Carnivore: small live and frozen foods such as daphnia, brine shrimp and bloodworm, plus fine flake

Swims

Top of the tank

Lifespan

4 to 6 years

Water

Freshwater

Wild range

Amazon and Orinoco basins and the Guianas (Brazil, Colombia, Venezuela, Guyana, Bolivia)

Breeding

It scatters eggs among fine-leaved plants and gives no parental care, and the adults will eat the eggs. Spawning in captivity is possible in soft, acidic water but is uncommon, and the tiny fry need infusoria at first.

Good to know

It is timid and has a small mouth, so keep it away from boisterous or large tankmates and use a tight lid, as it can jump.