Nannostomus Rubrocaudatus

Datasheet

General Description: Nannostomus rubrocaudatus, commonly known as the Purple Pencilfish, is a micropredator that feeds on tiny invertebrates and zooplankton in its natural habitat. It belongs to the family Lebiasinidae within the order Characiformes and exhibits pronounced sexual dimorphism in coloration, with adult males displaying red-purple pigmentation between dark lateral stripes.

Aquarium Setup

The Purple Pencilfish thrives in a heavily-planted aquarium with a dark substrate, broken lines of sight, floating plants, driftwood branches, and dried leaf litter. These features facilitate natural behavior, reduce skittishness, and provide refuges for sub-dominant individuals. Stable water conditions are vital, and a mature aquarium with gentle filtration is recommended (see table).

Behaviour: This species is peaceable with other fish but is best kept alone or with diminutive, non-aggressive species due to its timid nature. It is a shoaling species that displays territorial behavior, with males engaging in regular sparring. In confinement, aggression can lead to serious injury or death; hence, a spacious tank with adequate hiding spots is essential.

Feeding and Diet: Purple Pencilfish are micropredators that feed on small live and frozen foods like Artemia nauplii, Moina, and grindal worm. While they accept dried foods, a diet rich in small live or frozen fare should be offered regularly for optimal health.

Reproduction & Dimorphism: Reproduction in captivity is rare but feasible with proper conditioning and setup. Adult males are more colorful and less stocky than females, exhibiting a modified anal fin with thickened rays. Controlled breeding methods can increase fry yield, with fry requiring small live foods initially.

Habitat and Distribution: The species originates from the upper Amazon River in Peru, specifically from the Saramirisa region near the Andes foothills. Their exact habitat preferences remain unconfirmed, although related species prefer sluggish tributaries and rivers with dense aquatic vegetation and woody structures, particularly in lowland areas.

Etymology: The genus name Nannostomus is derived from the Latin "nannus" meaning small and Greek "stoma" meaning mouth, referencing the species' small mouthparts. The species epithet rubrocaudatus is from the Latin words for red (rubra) and tail (cauda), describing the red tail pattern of adult males.