Least pencilfish

Care at a glance

Overview

A tiny, peaceful pencilfish that lives in the midwater in a loose school. Keep it in a group of ten or so; small numbers leave it nervous and washed out, while a proper school stays coloured up and active. It suits a quiet community of other small, gentle fish, with nothing big enough to eat it or bustle it aside at feeding time. Its mouth is small, so feed fine foods: crushed flake, micro pellets, cyclops, daphnia and freshly hatched brine shrimp. Give the school a planted, softly lit tank of around 40 liters with gentle flow, dark substrate and plenty of cover to dart into.

In the wild

The least pencilfish comes from the tea-coloured forest creeks of Guyana, soft, acidic waters shaded by overhanging growth. Match that with warm water, about 24 to 28 C, and soft, acidic conditions around pH 5.0 to 6.5. A mature tank with dark substrate, driftwood, leaf litter and dense planting, dimly lit and gently filtered, brings out its best colour and keeps it at ease.

Good to know

Nannostomus minimus is a pencilfish, family Lebiasinidae, reaching under 3 centimeters, which puts it among the smallest of its genus. It is a shoaling micro-predator that takes tiny invertebrates and zooplankton, slender and marked with dark lengthwise lines. Spawning is an egg-scattering affair among fine-leaved plants and is little documented for this species in the aquarium. Its small size and soft-water needs put it a step beyond a beginner's fish.

Did you know

Described in 1909 and named for its small size, it was long thought the smallest pencilfish of all, until the even tinier Nannostomus anduzei turned up and bumped it into second place.

Tank mates

Least pencilfish is a peaceful, schooling species that keeps to the middle. These picks match on water type, temperature, pH, size and temperament.

• 

  Rose flame glassfish

  Gymnochanda verae

  Freshwater

  1.2 in (3 cm)11 gal (40 L)75–82°F (24–28°C)

• 

  Indian glowlight carplet

  Horadandia brittani

  Freshwater

  1 in (2.5 cm)11 gal (40 L)75–82°F (24–28°C)

• 

  Espei rasbora

  Trigonostigma espei

  Freshwater

  1.5 in (3.8 cm)11 gal (40 L)73–82°F (23–28°C)

• 

  Goblin sundadanio

  Sundadanio goblinus

  Freshwater

  0.9 in (2.3 cm)11 gal (40 L)73–81°F (23–27°C)

• 

  Dwarf scissortail rasbora

  Rasbosoma spilocerca

  Freshwater

  1.3 in (3.2 cm)11 gal (40 L)72–81°F (22–27°C)

• 

  Exclamation-point rasbora

  Boraras urophthalmoides

  Freshwater

  0.6 in (1.6 cm)11 gal (40 L)73–81°F (23–27°C)

Check the full mix in the stocking calculator

Common questions

Related species

• 

  Barred pencilfish

  Nannostomus espei

  Freshwater

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

• 

  Coral red pencilfish

  Nannostomus mortenthaleri

  Freshwater

  1.2 in (3 cm)15 gal (55 L)75–82°F (24–28°C)

• 

  Dwarf pencilfish

  Nannostomus marginatus

  Freshwater

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

• 

  Three-lined pencilfish

  Nannostomus trifasciatus

  Freshwater

  1.3 in (3.3 cm)15 gal (55 L)72–82°F (22–28°C)

• 

  Hockeystick pencilfish

  Nannostomus eques

  Freshwater

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

  Nannostomus digrammus

  Freshwater

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