This species has been referred to the genera Poecilobrycon and Nannobrycon in the past and in the aquarium hobby is also known as ‘rocket’, ‘brown’, ‘brown-tailed’, ‘diptail’, or ‘tubemouth’ pencilfish.It’s a popular aquarium fish and has an interesting oblique swimming-style, a behavioural trait shared only with N. unifasciatus among congeners.

In the original description the colour pattern is given by Steindachner as a brown lateral stripe exte…

This is the type species of the genus, fairly ubiquitous in the aquarium trade, and represents an excellent choice for the newcomer to fishkeeping since it’s less demanding than most congeners. It’s sometimes referred to as ‘Beckford’s pencil fish’ or ‘brown pencilfish’.

Don’t worry if your fish look different when you switch on the aquarium lights after dark or in the morning as like most Nannostomus species it assumes a cryptic, vertically-barred colour pattern at ni…