Barred Pencilfish Care Guide
Nannostomus espei · Freshwater Fish
What Barred Pencilfish look like
The Barred Pencilfish (Nannostomus espei) exhibits a slender, elongated, and laterally compressed body, reaching a maximum adult size of approximately 2 inches (5 cm). This species is characterized by its striking golden-brown coloration adorned with 4-5 prominent dark vertical bars, a unique feature among pencilfish, which typically display horizontal stripes. Notably, the fish undergoes a dramatic color change from barred during the day to striped at night, serving as a form of camouflage. Sexual dimorphism is subtle, with males generally being slightly smaller and exhibiting more vibrant coloration compared to females. The fish possesses a small, terminal mouth equipped with fine dentition suitable for grazing on small food particles. The dorsal fin is positioned far back, contributing to its streamlined appearance, while the anal fin is elongated, enhancing its agility in the water column. The presence of a lateral line system aids in detecting vibrations in the water, crucial for navigating its environment.
Behavior & temperament
Barred Pencilfish are typically found in small, loose schools, exhibiting a social hierarchy where dominant individuals may assert their presence through subtle displays of aggression. They inhabit the mid to upper water column in their natural habitat, often dwelling in slow-moving streams and flooded forests of South America. Their breeding behavior is characterized as an egg scatterer, where females release eggs among vegetation, and males fertilize them externally. These fish are generally peaceful but can display territorial behavior during breeding, making them suitable for community tanks with similarly sized and temperamental species.
Diet & feeding
In the wild, Barred Pencilfish are omnivorous, feeding on a varied diet that includes small invertebrates, zooplankton, and plant matter. In captivity, they thrive on high-quality flake food, live or frozen foods such as daphnia and brine shrimp, and finely chopped vegetables to ensure a balanced diet.
Behind the name
Nannostomus (small mouth); espei (named in honor of a person, often a contributor to ichthyology).
Plan your tank
Check the numbers before you buy: tank volume, a stocking plan, cycle progress, water changes, and your ongoing care routine.
Keeping Barred Pencilfish?
AquaLens identifies your fish and plants from a photo, tracks water chemistry, and flags health issues early — free on iOS and Android.
