Coral Red Pencilfish

Nannostomus mortenthaleri, the Coral Red Pencilfish, was described only in 2001 and originates from the blackwater Nanay River in Peru. Males display extraordinarily vivid coral-red to orange-red coloration across their flanks, contrasting with a bold black lateral stripe. It requires soft, very acidic blackwater conditions to show its best colour and remains healthy long-term. A true nano aquarium gem.

Water: 24–28°C, pH 4.5–6.5, very soft blackwater conditions essential for best colour and health. Tank: 40 L minimum; blackwater setup with peat or catappa leaves, dark substrate, dim lighting. Feeding: Micro-pellets, baby brine shrimp, micro-worms and small live invertebrates. Behaviour: Peaceful but males may spar; keep 6+ with more females than males. Compatibility: Nano fish only — small tetras, pygmy corydoras, dwarf shrimp in soft water.