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.
Compiled by Aquairi from published sources · Published · Updated
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.
Tube-mouth Pencilfish Breeding Guide
Overview
Nannostomus unifasciatus is a slender, oblique-swimming pencilfish from the upper Amazon and Orinoco systems and the Essequibo and Demerara rivers in Guyana. Seriously Fish records a size of 35-40 mm SL. It is a top-dwelling micropredator that prefers calm water.
Sexing
Males are more colourful and typically slimmer than females, with an enlarged anal fin (Seriously Fish). Females are rounder-bodied.
Conditioning
As a micropredator it should receive daily meals of small live and frozen fare such as Artemia nauplii, Moina and grindal worm alongside dried foods. Soft, acidic water suits it: Seriously Fish gives 23-28 C, pH 4.0-7.0 and hardness 18-179 ppm. The species is gregarious and best kept in groups of ten or more.
Common Challenges
Because confirmed spawning records do not exist and historical accounts likely referred to N. eques, no species-specific spawning trigger, egg behaviour or fry-rearing data can be cited for N. unifasciatus.