Most species are slender, pencil-shaped fish ranging in size from under 1 to about 2 in long. N. marginatus, N. rubrocaudatus, and N. mortenthaleri possess shortened, blockier outlines reminiscent of pencil stubs. All but one species, Nannostomu espei, possess one to five horizontal black or brown stripes with gold or silver iridescence appearing dorsal to the primary stripe. Most also display red, orange, or maroon highlights in their fins, and many have flashes of these colors on their flanks, as well. Nannostomus (from the Greek: nanno = small, stomus = mouth) is a genus of fish belonging to the Lebiasinidae family of characins. All of the species in this genus are known as pencil fish or pencilfish, a popular name that was first only applied to two species in the 1920s, Nannostomus unifasciatus and Nannostomus eques, but by the late 1950s would come to be applied to all members of the genus. Several of the species have become popular aquarium fish due to their attractive coloration, unique shape, and interesting demeanor. Nannostomus species thrive in home aquaria when provided with soft, moderately acidic water, low nitrate levels, and temperatures in the range of 72 to 82 F. The addition of aquatic plants, including floating varieties, is recommended. The latter will reduce the likelihood of the fish jumping, which is a common occurrence for some of the species, especially N. espei and N. unifasciatus. They should be kept in schools of at least six. If kept in a community aquarium, the best tankmates are other species of Nannostomus, small peaceful characins, and corydoras.

 

 

Nannostomus anduzei

Nannostomus beckfordi

Nannostomus bifasciatus

Nannostomus britskii

Nannostomus digrammus

Nannostomus eques

Nannostomus espei

Nannostomus grandis

Nannostomus harrisoni

Nannostomus limatus

Nannostomus marginatus

Nannostomus marilynae

Nannostomus minimus

Nannostomus mortenthaleri

Nannostomus nigrotaeniatus

Nannostomus nitidus

Nannostomus rubrocaudatus

Nannostomus trifasciatus