Black arrow tetra

Inpaichthys luizae

Also known as Luiza's tetra

FreshwaterFish

Care at a glance

Temperature: 72–81°F (22–27°C)
pH: 5.5–7.2
Adult size: 1.4 in (3.5 cm)
Minimum tank: 14 gal (54 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: No record
Rarity: Rare
Origin: Upper Rio Juruena, Tapajos basin, Mato Grosso, Brazil
Family: Characidae

Overview

A recently described dwarf tetra that behaves much like its close relative the royal tetra, this is a peaceful schooling fish for a group of at least eight to ten. It occupies the middle of the tank and shows its best smoke-blue color and dark arrow stripe over a dark substrate in soft, gently stained water. Keep it with other small, calm community fish such as pencilfish, small rasboras, corydoras, and dwarf cichlids. Feed small foods: micro pellets, crushed flake, and regular frozen or live daphnia, cyclops, and baby brine shrimp. A group is comfortable in around 54 liters or more.

In the wild

In the wild the black arrow tetra lives in clear, forested shield streams of Mato Grosso in central Brazil, shaded, soft, and slightly acidic. Reproduce that with warm water from 22 to 27 degrees Celsius and pH 5.5 to 7.2, a dark sandy or leaf-strewn bottom, driftwood, and dim lighting from overhead cover or floating plants. Gentle flow and clean, well-filtered water keep the group active and colored up.

Good to know

Inpaichthys luizae is a characin in the family Characidae reaching about 3.5 centimeters, and it sits in the same small genus as the royal tetra, Inpaichthys kerri. It was formally described only in January 2025, having reached hobbyists a year or two earlier under the trade name Black Arrow. Like its royal-tetra relative it is an egg-scattering spawner, and exporters report it breeds readily, though at-home records are still few.

Did you know

This fish was swimming in hobbyists' tanks as the Black Arrow tetra for a year or two before scientists formally described and named it in January 2025.