Home · Lebiasinidae · Oneline pencilfish
Oneline pencilfish (Nannostomus unifasciatus) — Lebiasinidae

Oneline pencilfish

Nannostomus unifasciatus
Family: Lebiasinidae
LC · Least Concern

The Oneline pencilfish (Nannostomus unifasciatus) is a freshwater fish of the family Lebiasinidae that grows up to 4 cm.

Length
3.8 cm
Water
Freshwater
Diet
Carnivore
Behaviour
Schooling
Activity
Diurnal
Body shape
Elongated (eel-like)
Substrate
Mixed bottom
Danger
Harmless
Edibility
Not eaten

Description

The oneline pencilfish is a small, elongate characin from northern South America, in the Amazon, Orinoco and Guianas basins. The species grows to about 6 cm and has a pencil-shaped, slender body with a continuous dark longitudinal stripe from snout to tail and a red-and-black mark in the lower tail lobe. Characteristically it often swims obliquely with the head up. It lives in calm, plant-rich blackwater streams and eats small zooplankton and insect larvae at the surface. It is a popular aquarium fish and is assessed as Least Concern (LC) by the IUCN.

Frequently asked questions

How do you recognise the Oneline pencilfish?

The Oneline pencilfish has an elongate, eel-like body, is mainly silver-grey and shows a horizontal stripes pattern.

Where does the Oneline pencilfish live?

The Oneline pencilfish lives in fresh water and is mostly found around mixed bottom.

How big does the Oneline pencilfish get?

The Oneline pencilfish grows to a maximum of about 4 cm.

Is the Oneline pencilfish dangerous to humans?

No, the Oneline pencilfish is harmless to humans.

Is the Oneline pencilfish edible?

The Oneline pencilfish is not usually eaten.

Download Fin's Fish Guide

Identify fish in seconds, log your catches and dives. Join the TestFlight beta.

Get the beta →

All data

Identification

Dutch name
Eenstreep-penseelvis verified
English name
Oneline pencilfish verified
Scientific name
Nannostomus unifasciatus
Family
Lebiasinidae
Other names
Oneline pencilfish; One-lined pencilfish; Pencil fish; Tail-eye pencilfish verified

Appearance

Size class
Small verified
Max length (cm)
3.8 verified
Body shape
Elongated (eel-like) sourced
Dominant colour
Silver / grey sourced
Pattern
Horizontal stripes sourced
Tail shape
Forked inferred
Mouth position
Superior (upward) sourced
Lips
Thin sourced
Barbels
No sourced
Dorsal fins
One continuous sourced
Dorsal spines
No sourced

Habitat & distribution

Water type
Freshwater sourced
Substrate
Mixed bottom sourced
Origin
Native verified

Behaviour & biology

Diet
Carnivore sourced
Social behaviour
Schooling sourced
Territorial
No sourced
Activity
Diurnal sourced
Reproduction
Separate sexes sourced
Sexual dimorphism
No sourced

For anglers

Edibility
Not eaten sourced
Fishing method
Geen doelsoort voor de hengelsport; hooguit incidentele vangst of bruikbaar als aasvisje. inferred
Regulations source
FishBase ↗ inferred

Safety

Danger to humans
Harmless sourced

Status & sources

Sources
FishBase via GBIF (DwC-A), CC-BY-NC 4.0

Same genus Nannostomus

More from the family Lebiasinidae

Download Fin's Fish Guide

Identify fish in seconds, log your catches and dives. Join the TestFlight beta.

Get the beta →