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Characins / Lebiasinidae / One-lined Pencilfish

One-lined Pencilfish
Nannostomus unifasciatus

Synonyms: Nannostomus unifasciatus, Poecilobrycon unifasciatus
Physical description: An elongated fish with a pale to olive brown back.   A fine, iridescent gold-colored line extends from the tip of the snout, through the eye and to the caudal fin.   Right below this line is a broad, black band that also extends from the snout, through the eye, and continues to the tip of the lower lobe of the caudal fin.  A small, black, oval spot is located on the upper lobe of the caudal fin. The belly is white in color. The anal fin is black with a white edging, while the other fins are transparent.
Size/Length: To 2.5" (6.5 cm)
Similar species: Three-striped Pencilfish ( Nannobrycon eques), Harrison's Pencilfish (Nannostomus harrisoni )
Habitat: Found in reedy shore vegetation usually in shallow parts of streams and small rivers.   South America; Rio Negro, Guyana; Amazon, Columbia, Brazil; tributaries of the Rio Madeira.
S: top
Aquarium: 20" (50 cm) or 10 gallons (38 L).   The tank should have open swimming areas with a partial cover of floating plants to diffuse lighting.   The tank should be well-planted and have a dark gravel bottom.  This species is somewhat sensitive to nitrates and nitrite so perform regular water changes.   These fish do best in peat-filtered water.
Water chemistry: pH 5-7 (6.5), dH 0-12 (4), 75-84°F (24-29°C)
Social behavior: A peaceful, schooling fish that should be kept in a group.   Combine with fishes of the lower swimming levels that are non-aggressive.
Suggested companions: Tetras, Corydoras, Loricarids, Killifish, Apistogramma, Discus.
FOOD: Live; Daphnia , insects, mosquito larvae, Artemia, Drosophila, glassworms, bloodworms; flake; freeze-dried.
SEX: The anal fin of the male red, white, and black, while the plumper female has a white and black anal fin.
Breeding techniques: See N. eques.
Breeding potential: 7. Breeding of this Pencilfish is somewhat more difficult than other Pencilfish
Remarks:  When water conditions are unfavorable, the colors of this fish may fade.   The One-lined Pencilfish swims in an oblique position.
Difficulty of care: 4.   A hardy fish that can be kept in a community tank with other non-aggressive fish.  This fish's diet needs to be regularly supplemented with live foods


By Rhett Butler   Mongabay.com