Species description

Care, breeding and tankmates

Fish profile

Temperament

Semi-aggressive

This species is extremely peaceful but can be very shy. They must be kept in schools of at least a half dozen to feel secure. When settled and kept with appropriate companions, they display fascinating swimming behaviors and a calm demeanor.

Diet

Carnivore

They are micro-predators requiring small meaty foods to thrive. Crushed flakes and micro-pellets are accepted, but frozen or live foods are vastly superior. Bloodworms, brine shrimp nauplii, and daphnia are excellent dietary staples.

Sex ratio

Group

Males are typically slimmer and may exhibit slightly more intense coloration than females. Keeping a higher ratio of females helps mitigate any mild inter-male aggression. In groups of six or more, any territorial behavior is harmlessly dispersed.

Feeding frequency

Twice daily

They possess very small mouths and stomachs, necessitating small, frequent meals. Feeding them two to three times daily is recommended to maintain their energy. Care must be taken to ensure they are actually getting food before faster fish consume it all.

Bioload

The One-line pencilfish contributes a very minimal bioload to the aquarium system. Their slight build means they process very little food into waste. They are ideal inhabitants for mature, delicate nano-aquarium ecosystems.

Flow

Stagnant

This pencilfish prefers slow-moving water reminiscent of their native sluggish streams. A strong current will cause them unnecessary stress and hinder their unique swimming style. Using a sponge filter or adjusting the output flow is the best approach.

Reproduction

Oviparous

Breeding is difficult and requires meticulous attention to water chemistry, specifically very soft and acidic water. They release their eggs among dense vegetation and offer no parental care. The adults must be removed immediately post-spawning to prevent them from consuming the eggs.

Compatibility & tankmates

This is a remarkably peaceful species that is well-suited for a tranquil community tank. Avoid aggressive, fast-swimming, or much larger tankmates that could outcompete them for food. Good tankmates include rasboras, small tetras, and peaceful bottom dwellers like Otocinclus.

Tank level

Top

They exhibit a unique behavior of swimming at an oblique angle near the water's surface. They generally occupy the top to middle levels of the water column. Tall, dense plants are appreciated as they love to rest among the leaves.