Marilyn's pencilfish

Nannostomus marilynae

Also known as Greenstripe pencilfish, Green striped pencilfish

FreshwaterFish

Marilyn's pencilfish (Nannostomus marilynae) — The Wet Spot Tropical Fish · Used with permission

Care at a glance

Temperature: 73–81°F (23–27°C)
pH: 5.0–6.8
Adult size: 2 in (5 cm)
Minimum tank: 14 gal (54 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: No record
Rarity: Rare
Origin: Upper Negro and Orinoco tributaries
Family: Lebiasinidae

Overview

A slim, elegant pencilfish that schools in the midwater and holds its body at a slight upward tilt, as pencilfish do. Keep it in a group of six or more so it schools naturally and shows its greenish side stripe; single fish hide and fade. It is peaceful and easygoing, a good fit for a soft-water community of small tetras, dwarf cichlids and other gentle fish. Feed small foods it can manage: crushed flake, micro pellets, cyclops, daphnia and baby brine shrimp. Give the school a planted, gently lit tank of around 54 liters with soft, acidic water and open midwater to swim in.

In the wild

Marilyn's pencilfish lives in soft, acidic, tea-stained waters of the upper Rio Negro and Orinoco tributaries in Brazil, Venezuela and Colombia, among sluggish backwaters and dense marginal plants. Keep it warm, about 23 to 27 C, and soft and acidic, around pH 5.0 to 6.8. A mature tank with dark substrate, driftwood, leaf litter and thick planting, softly lit, suits it well.

Good to know

Nannostomus marilynae is a pencilfish, family Lebiasinidae, reaching about 5 centimeters. A slim bronze fish, it is set apart from its many red-striped relatives by a green-toned lateral stripe, which earns it the common name greenstripe pencilfish. It feeds on small invertebrates in the wild. Spawning is not well documented for this species in aquaria, in common with many of the pencilfishes.

Did you know

The name honours Marilyn Weitzman, an American ichthyologist who worked on South American fishes alongside her husband Stanley; the species was described and named for her in 1975.

Tank mates

Marilyn's pencilfish is a peaceful, schooling species that keeps to the middle. These picks match on water type, temperature, pH, size and temperament.