Red Arc Pencilfish

Brittanichthys axelrodi is one of the most unusual and beautiful micro-characins in existence, native to the extreme blackwater streams of the Rio Negro drainage in Amazonas, Brazil. Despite its common name referencing pencilfish, it is not a true Nannostomus but is closely related. Its most striking feature is a bold, arching red stripe that traces along the upper half of the body, contrasting with transparent fins and a pale body.

Successful keeping demands a truly acidic, very soft blackwater setup: pH below 6.0, water that is nearly devoid of hardness, and rich in tannins. The fish is tiny and sensitive, and should be kept in a species or near-species tank with the most peaceful of community micro-fish. Groups of ten or more show the most natural behaviour.

Feeding uses only the finest micro-foods: baby brine shrimp nauplii, micro-powdered food, and Cyclops nauplii. This species rewards extreme dedication with extraordinary beauty.

Water: 25–29°C, pH 4.5–6.5, ultra-soft (GH 0–5, KH 0–2); blackwater with heavy tannins. Tank: 40 L minimum; blackwater species setup; zero to minimal flow, dim lighting, botanicals. Feeding: Baby brine shrimp nauplii, micro-powdered food, Cyclops nauplii — very small mouth. Breeding: Rarely achieved; requires ultra-soft blackwater conditions and finest live micro-foods. Compatibility: Species-only or with equally tiny soft-water micro-tetras and micro-rasboras.