Pencil fish

Lore & Background

The name "pencil fish" originally referred only to Nannostomus unifasciatus and Nannostomus eques in the 1920s, but by the late 1950s it was applied to all members of the genus Nannostomus, a group of small characins from South America. The genus was first described in 1872 by Günther, with Nannostomus beckfordi as the type species. Steindachner added three more species in 1876, and Eigenmann described four in 1909. Early popularity among aquarists was boosted by William T. Innes’s articles and photos from 1933.

The genus was later split into Poecilobrycon and Nannobrycon, but in 1975, Dr. Stanley Howard Weitzman and Dr. J. Stanley Cobb reunited all species under Nannostomus, a revision now widely accepted. Weitzman also described five newer species: N. marilynae, N. limatus, N. nitidus, N. britskii, and N. anduzei. Today, twenty species are known, most familiar to aquarists, though several unidentified Nannostomus have been imported as bycatch and remain taxonomically unresolved.

Did You Know?

• The name Nannostomus comes from the Greek nanos, meaning 'small', and the Latin stomus, relating to the mouth.
• The anal fin is generally a reliable indicator of gender; in most species, the anal fin of adult males is enlarged and elongated or more colorful.