One-Lined Pencilfish

Nannostomus unifasciatus

One-Lined Pencilfish is a peaceful middle-to-top swimmer. Keep in a school of 8+.

PeacefulMiddle to top swimmerKeep in a school of 8+Beginner – Intermediate

Save this fish or add it directly to one of your aquariums.

Quick facts

Adult size
≤ 7 cm (≤ 2.8 in)
Aquarium size
60 L or larger
Care level
Beginner – Intermediate
Temperament
Peaceful
Swimming zone
Middle to top swimmer
Temperature
23–28 °C
pH
4–7
GH
2–12 dGH
Diet
Omnivore
Lifespan
up to 5 years
Group behavior
Keep in a school of 8+

Care requirements

Care level: Beginner – Intermediate.

Lifespan: up to 5 years.

Aquarium size and space needs

Minimum aquarium size: 60 L or larger. Plan the layout and stocking within that limit.

Water parameters

Suitable water: temperature 23–28 °C, pH 4–7, GH 2–12 dGH.

Temperament and compatibility

One-Lined Pencilfish is peaceful and suits calm community fish.

Keep in a school of 8+.

Swimming zone and behavior

This fish uses the middle to upper part of the aquarium, so leave enough open swimming space for movement and feeding. Keep in a school of 8+.

Feeding

As an omnivore, One-Lined Pencilfish should receive a varied diet rather than one repeated food type.

Before adding this fish

  • Plan for an aquarium of 60 L or larger.
  • Make room for its social group.
  • Avoid aggressive or highly competitive fish.
  • Keep in a school of 8+.
  • Offer a varied diet that matches this species.

Similar fish profiles

Use these profiles to compare fish with similar care level, size, temperature range, or swimming behavior.

Barred Pencilfish Nannostomus espei Same genus Same family Similar care level Beginner – Intermediate ≤ 3 cm (≤ 1.2 in) 21–27 °C African Copper Ribbon Tetra Rhabdalestes septentrionalis Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 7 cm (≤ 2.8 in) 22–28 °C Allpahuayo Dwarf Cichlid Apistogramma allpahuayo Similar care level Same temperament Same swimming zone Intermediate ≤ 7 cm (≤ 2.8 in) 24–28 °C African Banded Barb Barbus fasciolatus Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 6 cm (≤ 2.4 in) 21–26 °C African Spottail Tetra Brachypetersius altus Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 6 cm (≤ 2.4 in) 22–26 °C Araguaia Corydoras Corydoras araguaiaensis Similar care level Same temperament Bottom dweller Beginner – Intermediate ≤ 6 cm (≤ 2.4 in) 21–26 °C

FAQ

How large does One-Lined Pencilfish get?

One-Lined Pencilfish reaches ≤ 7 cm (≤ 2.8 in).

What aquarium size does One-Lined Pencilfish need?

Use an aquarium of at least 60 L or larger.

Is One-Lined Pencilfish peaceful?

Yes. One-Lined Pencilfish is recorded as peaceful and is best planned with calm community fish that do not harass it or dominate the feeding area.

What temperature is suitable for One-Lined Pencilfish?

Keep it between 23 to 28 °C.

Should One-Lined Pencilfish be kept alone or in a group?

One-Lined Pencilfish: Keep in a school of 8+.

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