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…

This species can be told apart from relatives by the characteristic ‘keyhole’ shaped marking on each side of the body.

It’s one of few fishes in which the current generic name is derived from the common name popularised in the aquarium hobby with ‘Cleithracara‘ a combination of the Greek kleithron, meaning lock, and, acará, the Guaraní word for cichlids.