Nannostomus Harrisoni

Datasheet

General Description

The Blackstripe Pencilfish (Nannostomus Harrisoni) is a rare species in the aquarium trade, often exported accidentally with other species. It can be recognized by distinctive characteristics such as well-developed lateral stripes and a unique color pattern that changes from nocturnal to diurnal. Belonging to the family Lebiasinidae within the order Characiformes, these fish have a slender body, absent adipose fin, and a short anal fin base with males exhibiting specialized fins for courtship.

Aquarium Setup

The Blackstripe Pencilfish thrives in a heavily planted tank with dark substrate and floating vegetation. Driftwood branches and dried leaf litter can be added to mimic its natural habitat. A gentle filtration system is recommended, with air-powered sponge filters being sufficient. Water parameters should be maintained at 18-179ppm hardness, pH of 5.0-7.0, and a temperature range of 22-28°C (see table).

Behaviour

Although very peaceful, the Blackstripe Pencilfish is not the ideal community fish due to its small size and shy nature. It is best kept with similarly-sized, peaceful characids and small catfish species. They exhibit gregarious behavior and do well in groups of 10 or more, spreading out aggression within the group. Unlike some related species, rival males of the Blackstripe Pencilfish rarely engage in harmful sparring.

Feeding and Diet

In its natural habitat, the Blackstripe Pencilfish is a micropredator feeding on tiny invertebrates and zooplankton. In the aquarium, they accept dried foods but should also be offered live and frozen foods like Artemia nauplii and Moina. Daily meals of small live fare are beneficial for their diet and overall health.

Reproduction & Dimorphism

Reproduction of the Blackstripe Pencilfish can be achieved in a mature, densely planted aquarium. Controlled breeding setups with fine-leaved plants or wool mops can boost fry production. Mature males develop red pigmentation in pelvic, anal, and caudal fins, while females have hyaline pelvic and anal fins. Males are typically slimmer than gravid females.

Habitat and Distribution

These pencilfish inhabit sluggish tributaries, small rivers, and swampy areas, especially where dense aquatic vegetation, submerged structures, and leaf litter are present. The species is endemic to the Demerara River basin in eastern Guyana, including tributaries like Haiama River and Kuruabaru River. The Blackstripe Pencilfish is rarely found in the aquarium trade but can be a captivating addition for aquarists willing to accommodate its specific needs.