Harrison's Pencilfish

Nannostomus harrisoni

Also known as Harrison's Pencil Fish

Animalia›Chordata›Characiformes›Lebiasinidae

Harrison's Pencilfish is a small, slender South American fish known for its distinctive horizontal stripe and peaceful demeanor. These delicate fish are best kept in groups and thrive in heavily planted, dimly lit aquariums with soft, acidic water. They are excellent for planted tanks and community setups with other small, peaceful species.

Where it's from

Native to the Amazon, Demerara and Essequibo river basins

Brazil, Guyana and Venezuela

Recorded as introduced in Suriname (Surinam basin)

At a glance

Size: 1.4 in; 4 cm
Min tank: 10 gal; 38 L
Group: 6+
Temp: 72–79°F; 22–26°C
pH: 5.5-7.0
GH: 36–143 ppm; 2–8 dGH
Temperament: Peaceful
Swims: Top
Lifespan: 3-5 yrs

Ammonia 0 ppm and nitrate under 20 ppm.

Care

Diet

Harrison's Pencilfish are micropredators that feed on small live foods such as infusoria, micro worms, and small crustaceans. Supplement with high-quality micro pellets and finely crushed flake food. Feed small amounts 2-3 times daily, offering only what they can consume in a few minutes.

Behavior

These fish are shy and peaceful, preferring to stay in loose groups among dense vegetation. They exhibit a distinctive horizontal stripe along their body and are most active during low-light conditions. They rarely venture into open water and spend most of their time near plants and substrate.

Breeding

Breeding is challenging in home aquariums and requires very soft, acidic water (pH 5.5-6.5) and dense vegetation. Eggs are scattered among plants and parents do not provide care. Fry are extremely small and require infusoria or liquid fry food for the first weeks.

Tank mates

See all 5

Neon Tetra

Similar size and peaceful temperament; both prefer soft, acidic water

excellent

Cardinal Tetra

Comparable water requirements and non-aggressive behavior

excellent

Otocinclus

Small, peaceful bottom dweller that won't compete for food

excellent

Amano Shrimp

Peaceful invertebrate that helps with algae control and won't harm pencilfish

excellent

Java Fern

Provides essential shelter and shade that pencilfish require

excellent

Fits a 10-gallon tank Peaceful

No state or federal restrictions on record.

Not legal advice, and possibly incomplete or out of date. Rules vary by state and change over time; check with your state wildlife or agriculture agency before buying, keeping or shipping it.

The care information here is written with AI help, so it can contain mistakes. Spot one? Tell us and we'll fix it. Native range: Lista Roja de la Fauna Venezolana 2015 (CC BY 4.0); Tedesco et al. 2017 (CC0).