Three generic names are often encountered in relation to the pencilfishes that form the group to which Golden Pencilfish belongs: Poecilobrycon, Nannobrycon, and Nannostomus. Features, including the presence or absence of an adipose fin (Golden Pencilfish lacks this fin), presence or absence of a canal in one of the bones surrounding the eye (not directly observable in live specimens), relative length of the snout and angle of orientation when at rest or swimming (horizontal or angled upward, i.e. head-up) have all been cited as distinguishing characteristics. However, variability of some of these, e.g. presence/absence of an adipose fin, has led to considerable debate, with Poecilobrycon tending to be dropped and Nannobrycon being retained only by some ichthyologists for two species that exhibit the “head-up” characteristic, along with an enlarged lower caudal-fin lobe. Most authorities, however, tend to regard all the species concerned as members of a single genus, Nannostomus. Their peaceful nature and shoaling behavior make them attractive as aquarium fish, but pencilfishes are also desirable because of their two very different color patterns: one reserved for the daylight hours and one for the night.
Other common name
- Golden Pencilfish
- N. anomalus, N. aripirangensis, N. simplex
- Central Amazon, lower Rio Negro, and Guyana.
- Up to 2 1/2in (6.5cm) reported, but usually smaller.
- Peaceful shoaler; can be kept with lively tankmates as long as they are not predatory.
- Most small foods accepted, particularly livefoods.
- Well (but not excessively) planted, with reasonable amount of cover. Tolerant of a range of water and lighting conditions, but soft, acid water—preferably tannin-stained—and subdued illumination preferred. Temperature range: 75-82°F (24-28°C).
- Subdued lighting, soft, acid water and fine- leaved vegetation required. Water temperature: around 86°F (30°C). Eggs are scattered among vegetation and may be eaten by the spawners. Hatching takes 1-3 days.