Dwarf Pencilfish
Dwarf Pencilfish
Dwarf Pencilfish (Nannostomus marginatus) is the most widely kept and most beginner-accessible pencilfish — the small, elegant body displays three distinct horizontal stripes: gold above, red-orange in the middle, and a bold black lower stripe. At 1.2 inches it is one of the smallest Nannostomus species, ideal for nano blackwater setups.
Feeding & Care Tip: Hikari Micro Pellets (crushed or soaked briefly) and Sera Vipan Baby make excellent daily staples. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Baby Brine Shrimp and Hikari Frozen Daphnia. Pencilfish are slow, deliberate feeders — avoid fast tankmates that will outcompete them. Feed small amounts 2–3 times daily.
All Nannostomus species inhabit the blackwater and clearwater streams, lakes, and flooded forests of the Amazon and Orinoco basins — soft, acidic, tannin-stained water with dense vegetation and leaf litter. A mature blackwater setup with Indian almond leaves, dark substrate, and very soft slightly acidic water produces the most vivid coloration. Males are territorial with each other — keep more females than males and provide visual breaks with dense planting.
The oblique resting posture — head elevated, body angled downward at roughly 45 degrees — is a characteristic behavior of the Nannostomus genus. Schools adopt synchronized oblique positions at rest, which is both fascinating to observe and unmistakable once seen. The angle varies by species — some hold a gentle tilt while others are nearly vertical. Holds a moderate oblique angle. Keep in groups of 8+. Compatible with other small, slow-moving nano species.
One of the best nano fish for a blackwater planted aquarium.
Care & Ideal Parameters
| Difficulty | Easy — Moderate |
| Temperament | Peaceful — slow feeder; avoid fast tankmates |
| Typical Adult Size | 1.2 inches (3 cm) |
| Min. Group Size | 8 minimum — more females than males |
| Ideal Temp | 73–82°F (23–28°C) |
| Ideal pH | 5.0–7.0 |
| Ideal GH | 0–10 dGH |
| Ideal KH | 0–5 dKH |
| Staple Food | Hikari Micro Pellets (crushed/soaked); Sera Vipan Baby |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Baby Brine Shrimp; Hikari Frozen Daphnia |
| Origin | Amazon and Orinoco basins, South America |
| Notes | Most widely kept Nannostomus. Three distinct horizontal stripes. Most beginner-accessible pencilfish. |
