铅笔鱼属（学名：Nannostomus），又名小口脂鲤属（其学名取自希腊语：nanno = 小，stomus = 口），是辐鳍鱼纲脂鲤目脂鲤亚目鳉脂鲤科（又称短嘴脂鲤科）之下的一个属。「铅笔鱼」这名称沿于1920年代，是本属两个当时已知品种* 单线铅笔鱼 （Nannostomus unifasciatus）及管口铅笔鱼（Nannostomus eques）的别称，及至1950年代成为了整个属的名称。由于本属物种的颜色抢眼，形态独特，使之成为水族箱的宠儿。

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.