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Fish Freshwater Care: medium Peaceful

Three-lined Pencilfish

Nannostomus trifasciatus
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Other names: Threestripe pencilfish
Group: Tetras and characins · Family: Lebiasinidae · Origin: South America — Amazon basin, Rio Negro and the Guiana region

An elegant pencilfish with three dark horizontal lines on its slender, pencil-shaped body and bright red spots at the fin bases. It needs soft water and calm tankmates.

Will it suit my tank?

Last updated October 16, 2026

Temperature
24–28°C
pH
5–7
Hardness
1–10 dGH
Adult size
5 cm
Minimum tank size
60 liters
Lifespan
4–6 years
Social structure
School
Group
at least 6, ideally 10+
Swimming zone
Middle
Diet
Omnivore
Breeding
Egg scatterer

Water parameters

Temperature24–28°C
pH5–7
General hardness (GH)1–10 dGH
Recommended range
May escape, needs a lid Considered shrimp safe Suitable for planted tanks

Overview

October 16, 2026 · Suggest an edit

The three-lined pencilfish is recognized by one main and two thin dark lines running along its slender, elongated body, with gold stripes between the lines. There are bright red spots at the base of the dorsal, anal, pelvic and tail fins. It is one of the most colorful pencilfish. At night its coloration changes and the lines are replaced by dark blotches.

Tank Setup

October 16, 2026 · Suggest an edit
  • At least 60 liters for a group of 6–10.
  • 24–28°C, pH 5–7, soft water.
  • Dense plants, floating plants, roots and dim light.
  • It is a good jumper; a lid is required.

Diet

October 16, 2026 · Suggest an edit

Its mouth is small. Fine flakes, micro granules, frozen cyclops, daphnia and newly hatched brine shrimp are suitable. It mostly takes food from the upper and middle layers; feed small amounts 1–2 times a day.

Behavior and Compatibility

October 16, 2026 · Suggest an edit

Peaceful and calm. Males set up small territories and put on harmless displays to each other. When kept with fast, greedy species, it loses out at feeding time.

Good companions: small tetras, other pencilfish, rasboras, corydoras, otocinclus, dwarf cichlids, shrimp.

Avoid: fast and greedy species, fin nippers, large predators.

A short profile for this species

The Three-lined Pencilfish page has the basics, but the sections below have not been written yet. If you keep this species, write a section from your own experience; it will be published under your name after editor approval.

Tank mates

This list is calculated automatically from the species profile and grows as new species are added to the catalog. Try it in the planner for a definite answer.

Usually compatible

Should not be kept together

Hobbyist notes

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Change history and contributors
  1. Page created · October 16, 2026