In a study conducted on the Arataye River, the main tributary of the Approuage, this species was mostly collected from stretches of rapids with rocky substrate which were reduced to a series of pools during the dry season. Other fishes observed at the same site were Auchenipterus nuchalis, Hypostomus gymnorhynchus and Moenkhausia cf. intermedia while at other localities in the river Bryconops affinis, Myleus ternetzi, M. rhomboidalis, Moenkhausia aff. barbouri, Curimata sp. and Serrasalmus sp. were collected.

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…