One-lined Pencilfish (The Ultimate Guide for Aquarists)

One-lined Pencilfish

One-lined Pencilfish, scientifically known as Nannostomus unifasciatus, is a freshwater fish with a unique mouth.

Its name comes from Greek and Latin words meaning “small” and “mouth,” as well as “one band” for its appearance.

It belongs to the Nannostomus genus in the Lebiasinidae family.

One-lined Pencilfish are popular for aquariums because they’re small, colorful, have interesting swimming patterns, and are easy to care for.

They have a slim shape like a pencil, with one black stripe along their body that looks like graphite in a pencil, and an eraser-colored tail fin.

The term “Pencilfish” was first used to describe this species in the 1920s but now refers to all fish in the Nannostomus genus.

One-lined Pencilfish feeds on worms, crustaceans, and insects in the wild.

One-lined Pencilfish Interesting Facts

  • One-lined Pencilfish is a small, colorful aquarium fish with a unique mouth and a black stripe along its body.
  • Native to South America, it lives in slightly acidic freshwater environments near the bottom.
  • Ideal water conditions for this fish include pH of 5.5 to 7.0, hardness up to 4 dH, and temperature between 77°F to 82°F (25°C to 28°C).
  • It feeds on worms, crustaceans, and insects in the wild.

One-lined Pencilfish Habitat

One-lined Pencilfish is a small fish found in South America, specifically in parts of the Amazon basin in Bolivia, Brazil, Colombia, Venezuela’s upper Orinoco basin, and Guyana.

Its scientific name is Nannostomus unifasciatus. This fish lives in freshwater environments close to the bottom (benthopelagic) and prefers slightly acidic water with a pH range of 5.5 to 7.0.

The water hardness (dH) should be up to 4, and the ideal temperature for this tropical fish is between 77°F to 82°F (25°C to 28°C).

Water Temperature:77°F to 82°F (25°C to 28°C)
Water pH:5.5 to 7.0 pH
Water Hardness:Unknown

One-lined Pencilfish Physical Characteristics

Size: 1.5 inches (3.8 centimeters)

One-lined Pencilfish is a small aquarium fish that grows up to a maximum length of 1.5 inches (3.8 centimeters).

One-lined Pencilfish Scientific Classification

Scientific Name:Nannostomus unifasciatus
Also Known As:One-lined Pencilfish
Conservation Status:Unknown

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