Pencil fish

Nannostomus (from the Greek nanos, meaning "small", and the Latin stomus, relating to the mouth) is a genus of fish belonging to the characin family Lebiasinidae. All of the species in this genus are known as pencil fish, a popular name that was initially only applied to two species in the 1920s, Nannostomus unifasciatus and Nannostomus eques. By the late 1950s, however, the term was applied to all members of the genus. Several species have become popular aquarium fish due to their attractive coloration, unique shape, and interesting demeanor.