Two-Lined Pencilfish

About

The two-lined pencilfish (Nannostomus bifasciatus) is a slender, torpedo-shaped characin from the coastal river systems of Suriname and French Guiana, where it tends to favor upstream stretches with some current. Like other pencilfish, it carries a pair of bold horizontal stripes along its flanks, but what really catches the eye in a group setting is its habit of angling the body upward while swimming. A quirky posture that makes a school of them look like a living mobile. It is genuinely gregarious, forming tight schools in the wild, and this social nature carries over into the aquarium. A group of ten or more will behave far more naturally and confidently than a smaller cluster. Despite being labeled as schooling, this species does have a reputation for scrappiness. Conspecific squabbles are common, especially in smaller groups or cramped quarters, which is part of why a 20-gallon minimum is worth taking seriously. It is crepuscular, meaning it tends to be most active around dawn and dusk. Diet-wise it leans toward insect-based foods in the wild, so small live or frozen invertebrate foods like daphnia or bloodworms will be well received alongside quality dried foods. Intermediate-level experience is a fair expectation here.