One-line Pencilfish

Geographic Origin and Biotope: Rio Negro region and central basin (Brazil), French Guiana, Bolivia. Shares muddy and turbid lagoons covered with reeds and shrubs with the *N. eques* species.

Taxonomy and Morphology: One-lined Pencilfish (Nannostomus unifasciatus). Slender and filiform pencilfish (up to 5 cm / 2 inches). Like the eques, it shares the very special oblique posture.

Social Behavior: The diagonal hunter (Diptail posture). Swims at 45 degrees towards the surface, stationary in a thick school waiting for prey in unison.

Coloration and Sexual Dimorphism: Compared to the eques (which has a white belly and is marbled brown), the unifasciatus is clean pale silvery/transparent, cut in two by a very clear and elegant continuous black line (Unifasciatus - one line). Males have bright red flames on the anal fin and on the lower lobe of the tail (females are pale or with very little red).

Aquarium Setup: Surface/Igapo species. Requires thick layers of Limnobium laevigatum or Salvinia. The lighting must be shielded and the current (Especially on the surface) absent, or they will fight the inclination, exhausting themselves.

Diet and Feeding: Pure surface feeder. They will NEVER pick up food on the bottom. The food must float for a long time. Freeze-dried Drosophila, fine flakes deposited on the surface or small nauplii. The upper mouth is small and ill-suited for large granules.

Water Quality: As fragile as the eques. Requires an acidic environment (pH 5.5-6.5) to ward off parasites and stress. The addition of peat, alder cones and dry leaves on the bottom is fundamental.

Compatibility and Tankmates: Strictly peaceful. Coexists with other small South American inhabitants but suffers from food competition. Ideal companions: Corydoras (who clean the bottom that he ignores), small Loricariids and other Nannostomus.

Aquarium Reproduction: They spawn by turning upside down under large water lily leaves or woods (exactly like the eques). Very tiny fry that hover near the nest.

Risks and Diseases: Starvation. One of the fish with the highest post-purchase starvation rate. Often, for an entire month it will ignore dry food waiting for live food. Whoever buys it must provide it with live cultures before attempting the transition to high-quality floating dry food.