Encyclopaedia
Dwarf pencilfish
Nannostomus marginatus
The smallest of the pencilfish: at just 2.5–3 cm, it is a nano-jewel perfect for small planted aquariums. The body is crossed by three horizontal black bands interspersed with golden and red stripes — a refined graphic design in miniature. Like all Nannostomus, it displays the nocturnal livery change: spots and bars appear in the dark and disappear in light. Prefers soft, acidic water (pH down to 4.0 in nature). In schools of 8+ on dark substrate with floating plants, the effect is aquatic terrarium-grade.
- Family
- Lebiasinidae
- Origin
- Brasilien, Peru, Kolumbien, Venezuela, Guyana, Surinam
- Origin
- Amazon, Orinoco, and Guianas
- Tank use
- Used in 0 tanks
Share
24 °C - 28 °C
5.5 - 7
Freshwater
Surface and middle
3.5 cm
Description
Geographic Origin and Biotope: Lower/central Amazon and Orinoco Basin (Peru, Colombia, Brazil). Inhabits oxbow lakes, black ponds and marginal river zones with very slow flow, among roots and foliage.
Taxonomy and Morphology: Dwarf Pencilfish (Nannostomus marginatus). Extremely compact and stocky pencilfish (the shortest after the anduzei), 3-3.5 cm (1.2-1.4 inches) max, with a very convex profile.
Social Behavior: The most sociable and "lively" among the small pencilfish. Forms very close-knit groups, hides and darts quickly among the leaves (unlike the static species in suspension).
Coloration and Sexual Dimorphism: Trichromatic, three black stripes (dorsal, conspicuous central, abdominal) interspersed with gold bands. Distinctive element: the anal and dorsal fins have distinct red flashes edged with black. Males are brighter; at night they assume the typical oblique bands.
Care and observations
Aquarium Setup: 60 cm (24 inches) tank. Java moss, floating plants and rocks/woods are mandatory. If they do not perceive visual barriers in the tank they will stay at the bottom in the grip of terror (fading).
Diet and Feeding: Omnivores, but with a tiny mouth. Very inclined to also accept dry food (unlike the harrisoni or eques), as long as it is crumbled into powder. Excellent integration with microworms.
Water Quality: Tolerant and adaptable, they live well in amber or crystal clear water. They prefer ph 6-6.5 but tolerate neutral, making them excellent candidates for novices compared to other Nannostomus species.
Compatibility and Tankmates: Perfect pacifists (Community nano-fish). Often used by great Aquascapers (Amano style) in dense planted tanks together with adult Caridina, Otocinclus, and Iriatherina (Threadfin Rainbowfish).
Aquarium Reproduction: Possible in dedicated aquarium with a mop (green synthetic fiber). They lay 2-3 eggs daily. Immediately separate the breeders, avid devourers of their eggs.
Risks and Diseases: Parasite attacks from water stress (Velvet/Ich). If water changes are too infrequent and filter flow is excessive, the marginatus's immune system (being a "puddle" fish) will collapse rapidly.
Fish profile
- Temperament
- Molto pacifico e gregario. Tenere in banchi di almeno 6–10
- Diet
- Micro-predatore con bocca minuscola: micro-pellet, fiocchi tritati, nauplii di artemia, dafnia, ciclopi, micro-vermi vivi o surgelati
- Tank level
- Surface and middle
- Minimum group
- 6
- Adult size
- 3.5 cm
- Minimum tank
- 40 L
- GH
- 1 dGH - 10 dGH
- KH
- n/a
- TDS
- n/a
- Conductivity
- n/a
- Feeding frequency
- 2 volte al giorno
- Bioload
- Negligible
- Flow
- Corrente debole a assente
- Jump risk
- Covered tank required
- Reproduction
- Vasca dedicata con acqua morbida e acida (pH 6.0–6.5). Piante a foglia fine o mop. Deposizione al mattino presto. Oviparo a dispersione. Rimuovere genitori. Schiusa 24–48 ore. Avannotti estremamente piccoli: infusori, cibo in polvere, poi nauplii di artemia.
- Compatibility
- Ideale con tetra nano, rasbore, Celestial Pearl Danio, Corydoras, gamberetti nani.
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.