Dwarf Pencilfish
Nannostomus marginatus
Tiny, boldly striped pencilfish that thrives in groups and rewards patient keepers.
About
The dwarf pencilfish (Nannostomus marginatus) is one of the smallest members of its genus, but what it lacks in size it more than compensates for in personality when kept in a proper group. Native to a broad stretch of South America spanning the Amazon basin, Guyana, Suriname, Colombia, Venezuela, and Peru, it typically inhabits calm, shaded waters with soft, acidic conditions. The body is compact and stubby compared to other pencilfish, marked by three dark horizontal stripes running from snout to tail with no red or purple coloration between them in males. Which is a handy way to tell this species apart from close relatives like N. mortenthaleri and N. rubrocaudatus. One charming quirk worth knowing: switch the lights on after dark and you may barely recognize your fish. The bold stripes fade at night, replaced by two oblique bars near the dorsal fin, a hardwired diurnal color shift the fish cannot voluntarily control. Despite being genuinely peaceful, this species does better in a species-focused or carefully chosen community rather than a mixed tank with larger or boisterous fish. Groups of ten or more bring out bolder behavior and distribute any mild male rivalry harmlessly. It also works beautifully as a dither fish alongside dwarf cichlids. Breeding is possible but requires some effort and patience.
Similar species
Other fish you might consider
Good tank mates
Species that tend to coexist peacefully with Dwarf Pencilfish
From the same region
Share the same natural habitat. Great for a biotope-themed tank
Frequently asked questions
- How big does the Dwarf Pencilfish get?
- The Dwarf Pencilfish reaches about 1–1.5" as an adult.
- What size tank does the Dwarf Pencilfish need?
- A minimum of 11 gallons is recommended for the Dwarf Pencilfish, with more room needed for a proper group.
- What water parameters does the Dwarf Pencilfish need?
- The Dwarf Pencilfish does best with a temperature of 72–82°F, a pH of 4–7.5, hardness around 1–15 dGH.
- Is the Dwarf Pencilfish aggressive?
- The Dwarf Pencilfish is generally peaceful and suits a community tank with similarly calm tankmates.
- What does the Dwarf Pencilfish eat?
- The Dwarf Pencilfish is an omnivore. It does well on a varied diet of quality flake or pellet plus occasional frozen or live foods.
- How long does the Dwarf Pencilfish live?
- With good care, the Dwarf Pencilfish typically lives 1-5 years.