Species profile
Dwarf Pencilfish
Nannostomus marginatus
Peaceful
Moderate care
60 L minimum aquarium
2.5–3.5 cm adult size
Top mid
Minimum group: 10
About this species
General notes for hobby use.
Tiny pencilfish; a proper shoal and low-pressure feeding environment matter more than squeezing it into the smallest possible volume.
Water parameters
Suggested general range for long-term care.
Temperature
24–27 °C
pH
5.5–7.2
GH
0–10 dGH
KH
Not yet documented
Flow preference
Low
Data confidence
Verified
Behaviour
General behaviour traits used by TanksConnected compatibility checks.
Minimum group size
Minimum group: 10
Tank zone
Top mid
Territory level
None
Predation risk
Tiny fry
Bioload factor
0.35
Peaceful and somewhat shy. Dense cover and a group of ten or more produce much more natural behaviour.
Compatibility flags
Quick cautions for common tank-planning issues.
Fin nipper
No
Plant safe
Yes
Shrimp safe
Yes
Snail safe
Yes
Cave breeder
No
Digs substrate
No
Jump risk
Yes
Natural history & care
Research-backed context for long-term aquarium care.
Lifespan
Not yet documented
Diet type
Omnivore
Minimum aquarium volume
60 L
Minimum footprint
60 × 30 cm
Accepted scientific name
Nannostomus marginatus
Alternative names
Dwarf Pencilfish, Marginatus Pencilfish
Native range
Amazon and Guiana Shield drainages in northern South America.
Natural habitat
Soft, quiet forest-edge water with leaf litter and vegetation. Use a mature planted/botanical setup with subdued light.
Diet & feeding
Very small dry foods plus Artemia, Daphnia, Cyclops and other microfoods.
Breeding & sexing
Research-backed guidance for identifying sexes and reproductive behaviour.
Sexing
Males are generally slimmer and more intensely patterned; females are fuller.
Breeding
Egg-scatterer among fine plants; eggs and fry are vulnerable to adult predation.