Diptail Pencilfish

Geographic Origin and Biotope: Central Amazon Basin (Brazil, Peru, Colombia). Exclusively populate the surface of swamps ("Igapó") and slow streams (Igarapés), hiding under huge floating carpets (Salvinia, Pistia).

Taxonomy and Morphology: Brown Pencilfish / Diptail (Nannostomus eques). The king of imitation: shape and posture replicate a twig. Superior mouth (to eat from under the surface of the water) and short digestive tract.

Social Behavior: Unmistakable posture: they swim (or rather "hang") inclined at 45 degrees with their snout pointing upwards to the surface. They move in jerks all together (schools of 10+), giving the illusion of debris drifting adrift.

Coloration and Sexual Dimorphism: Woody brownish color on top, with an opaque silvery belly for camouflage against predators from below. At night the dark stripes fade into oblique patches. Males have a much more intense red/brown coloration on the anal fin.

Aquarium Setup: Tank (minimum 80 cm / 32 inches) strictly filled with floating plants and Pistia. If kept under bare light (without floaters) they will perish from stress darting away at the first passage of shadows. No strong surface current or they won't be able to stay in trim (45 degrees).

Diet and Feeding: Specialized surface hunter. They wait motionless for midges or springtails to fall on the water. In the tank they eat Drosophila, pulverized high-end flakes floating, or freeze-dried micro pellets (as long as they don't sink).

Water Quality: Acidic Blackwater. They are extremely prone to parasites if the water is alkaline (Ph > 7.0). The tannins released by the dry leaves on the bottom are indispensable as a natural antibacterial for this wild species.

Compatibility and Tankmates: Strictly peaceful. They bother no one, but are slow to feed. Excellent with Hatchetfish (Carnegiella), small tetras (Cardinals, Nematobrycon) or Dwarf Cichlids (Apistogramma cacatuoides).

Aquarium Reproduction: Curious: they lay sticky eggs UNDER broad floating leaves, turning upside down to attach them (Corydoras style). The larvae will hide among the floating roots of the Pistia requiring rotifers.

Risks and Diseases: Open tank decay. "Diptails" jump instinctively to escape or hunt, but often do so even just if frightened by roommates. Strictly fitting lid with no gaps.