Three-lined pencilfish

Care at a glance

Overview

Keep it in a group of at least six, ideally more, in a tank around 55 liters with plenty of plant cover. It holds in the middle and upper water and can be shy, so it shows best in a calm setup. Water should be soft and acidic, pH 5.5 to 7, at 22 to 28 C. Its mouth is tiny, so feed small foods: micro-pellets, fine flake, and little live or frozen items like daphnia, baby brine shrimp, and microworms. It is gentle and suits a quiet, similar-sized community.

In the wild

The three-lined pencilfish lives in slow blackwater streams and tributaries of the Amazon basin, in Brazil, Peru, and Colombia. The water there is acidic, soft, and stained brown with tannins, with leaf litter and plants everywhere. To match it, run a dim, planted tank with driftwood, dried leaves, and maybe some peat or botanicals to soften and tint the water. Keep it in the low to high 20s C.

Good to know

This is a pencilfish in the family Lebiasinidae, a slim, small species reaching only about 3.3 cm. It has three dark horizontal stripes down a slender body. Like other pencilfish, its day pattern shifts at night into a blotchy resting pattern. It is an egg-scattering species that is moderately tricky to breed.

Did you know

Pencilfish change their look between day and night. The clear daytime stripes break up into a spotted or banded pattern after lights-out, which can be a surprise the first time you check the tank in the dark. It's a normal resting color, not stress.

Related species

• 

  Hockeystick pencilfish

  Nannostomus eques

  1.4 in (3.5 cm)15 gal (55 L)72–82°F (22–28°C)
• Twostripe pencilfish

  Nannostomus digrammus

  1.4 in (3.5 cm)12 gal (45 L)75–82°F (24–28°C)

• 

  Barred pencilfish

  Nannostomus espei

  1.2 in (3 cm)15 gal (55 L)72–82°F (22–28°C)

• 

  Coral red pencilfish

  Nannostomus mortenthaleri

  1.2 in (3 cm)15 gal (55 L)75–82°F (24–28°C)
• One-lined Pencilfish

  Nannostomus unifasciatus

  1.6 in (4 cm)17 gal (65 L)73–82°F (23–28°C)

• 

  Dwarf pencilfish

  Nannostomus marginatus

  1 in (2.5 cm)12 gal (45 L)72–82°F (22–28°C)