Flag Tetra

Hyphessobrycon heterorhabdus

Also known as Belgian flag tetra

FreshwaterFish

Flag Tetra (Hyphessobrycon heterorhabdus) — Carl H. Eigenmann · Public domain

Care at a glance

Temperature: 70–81°F (21–27°C)
pH: 5.5–7.0
Adult size: 1.4 in (3.5 cm)
Minimum tank: 16 gal (60 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: Medium
Rarity: Rare
Origin: Colombia, Brazil
Family: Characidae

Overview

Keep them in a group of at least six to eight so they school and feel safe. They are peaceful mid-water fish but a bit sensitive to water quality, so they reward stable, soft, slightly acidic conditions and steady maintenance. Feed quality flake, small pellets, and frozen foods like bloodworm or daphnia. Aim for temperatures in the low to high 20s C and a tank of around 60 liters for a school.

In the wild

Flag tetras live in the lower Amazon basin across Colombia and Brazil, in slow streams, rivers, and flooded forest. The water is soft and slightly acidic, shaded by the canopy and often stained with tannins over leaf litter. Recreate that with a planted tank, driftwood, dim lighting, and a darker substrate. Soft water from pH 5.5 to 7 keeps them settled and showing color.

Good to know

A characin in the family Characidae, reaching about 3.5 cm. It is marked by a gold-over-red line running the length of the body with a black stripe beneath it, the pairing that gives the flag its name. They are egg scatterers with no parental care, and they spawn among fine-leaved plants. They are considered a moderately demanding tetra to keep and breed.

Did you know

The flag tetra's red and gold stripe acts as a water-quality readout. When conditions are clean and stable the line glows bright, but stress, poor water, or a harsh bare tank makes it fade fast, so a dull flag tetra is often telling you to check the tank before the fish looks sick.