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Tube-mouth Pencilfish Care Guide

Nannostomus unifasciatus is a slender oblique-swimming pencilfish with a single black lateral stripe, native to the upper Amazon and Orinoco systems.

Overview

Nannostomus unifasciatus is a slender, stick-shaped pencilfish of the family Lebiasinidae, marked by a single black lateral stripe. With Nannostomus eques it is one of only two pencilfishes that habitually adopt an oblique swimming posture. FishBase gives a maximum standard length of about 3.8 cm.

Taxonomy

  • Family: Lebiasinidae
  • Genus: Nannostomus
  • Scientific name: Nannostomus unifasciatus (Steindachner, 1876)

Habitat

FishBase and Seriously Fish place the species across the upper Amazon basin of Bolivia, Brazil and Colombia, the upper Orinoco system of Colombia and Venezuela, and the Essequibo and Demerara rivers of Guyana. It inhabits calm, vegetated waters.

Tank requirements

  • Minimum tank volume: 80 L
  • Temperature: 23-28 °C (73-82 °F)
  • pH: 5.0-7.0
  • GH: 1-8 °dGH (soft water)
  • School size: 6 or more, ideally 10 or more
  • Lifespan: 3-5 years
  • Calm, planted tank with low flow suits this surface species

Diet

Seriously Fish describes Nannostomus unifasciatus as a micropredator on tiny invertebrates. In aquaria it should receive daily meals of small live and frozen fare such as Artemia nauplii, Moina and grindal worm, supplemented with suitably sized dried foods.

Compatibility

The species is very peaceful but timid, and assumes a cryptic, vertically barred colour pattern at night. Keeping ten or more spreads any minor aggression and encourages bolder behaviour. Suitable companions include small peaceful characids, dwarf cichlids such as Apistogramma, and small catfishes.

Breeding

Seriously Fish reports that the species is not confidently known to have been bred in captivity, with earlier accounts likely confused with the congener Nannostomus eques.

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