Redmouth Pencilfish

Nannostomus nigrotaeniatus

Redmouth Pencilfish is a peaceful middle swimmer. Keep in a loose group of 8+.

PeacefulMiddle swimmerKeep in a loose group of 8+Beginner – Intermediate

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

Need help with Redmouth Pencilfish?

Explore compatibility, care or problems using this guide and your aquarium’s conditions.

Quick facts

Adult size: ≤ 1.6" (≤ 4 cm)
Aquarium size: ≥ 23.6" (≥ 60 cm) minimum length
Care level: Beginner – Intermediate
Temperament: Peaceful
Swimming zone: Middle swimmer
Temperature: 75–82°F (24–28°C)
pH: 5.5–7
GH: 2–10 dGH
Diet: Omnivore
Lifespan: up to 5 years
Group behavior: Keep in a loose group of 8+

Care requirements

Care level: Beginner – Intermediate.

Lifespan: up to 5 years.

Water parameters

Suitable water: temperature 24–28 °C, pH 5.5–7, GH 2–10 dGH.

Temperament and compatibility

Redmouth Pencilfish is peaceful and suits calm community fish.

Swimming zone and behavior

This fish uses the middle part of the aquarium, so leave enough open swimming space for movement and feeding.

Before adding this fish

Plan for an aquarium of ≥ 23.6" (≥ 60 cm) minimum length.
Make room for its social group.
Avoid aggressive or highly competitive fish.
Keep in a loose group of 8+.
Offer a varied diet suited to this species’ documented feeding habits.

Natural habitat and origin

Origin: Venezuela.

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 ≤ 1.2" (≤ 3 cm) 72–82°F (22–28°C) Bleeding Blue Tetra Hyphessobrycon margitae Similar care level Same temperament Same swimming zone Beginner – Intermediate 1.6–2" (4–5 cm) 73–79°F (23–26°C) Blueberry Tetra Hyphessobrycon wadai Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 1.6" (≤ 4 cm) 75–81°F (24–27°C) Black Arrow Royal Tetra Inpaichthys luizae Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 1.6" (≤ 4 cm) 72–79°F (22–26°C) Black Heart Tetra Hyphessobrycon copelandi Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 1.6" (≤ 4 cm) 75–82°F (24–28°C) Black Line Tetra Hyphessobrycon scholzei Similar care level Same temperament Same swimming zone Beginner – Intermediate ≤ 1.6" (≤ 4 cm) 72–82°F (22–28°C)

FAQ

How large does Redmouth Pencilfish get?

Redmouth Pencilfish reaches ≤ 1.6" (≤ 4 cm).

What aquarium size does Redmouth Pencilfish need?

Use an aquarium of at least ≥ 23.6" (≥ 60 cm) minimum length.

Is Redmouth Pencilfish peaceful?

Yes. Redmouth 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 Redmouth Pencilfish?

Keep it between 24 to 28 °C.

Should Redmouth Pencilfish be kept alone or in a group?

Redmouth Pencilfish: Keep in a loose group of 8+.