Rainbow bitterling

Acheilognathus macropterus

Also known as Giant bitterling, Largefin bitterling

FreshwaterFish

Care at a glance

Temperature: 57–79°F (14–26°C)
pH: 6.5–7.8
Adult size: 10.6 in (27 cm)
Minimum tank: 106 gal (400 L)
Temperament: Mostly peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: Hard
Rarity: Rare
Origin: Amur to Yangtze river systems, East Asia
Family: Acheilognathidae

Overview

The rainbow bitterling is a coolwater schooling fish that reaches a surprising size, so it needs pond-scale space rather than a small aquarium. Keep it in a group of six or more, since it shoals by nature and grows calmer and more colorful in a crowd. It swims in the middle water and is generally peaceful, though a fish this large should share space only with other sizable, temperate tankmates. Feed it as an omnivore, with frozen foods, sinking pellets, flake, and vegetable matter. It does best cool and planted, with a winter rest. A group needs a large tank or pond of around 400 liters or more.

In the wild

The rainbow bitterling cruises weedy backwaters and slow rivers across East Asia, from the Amur south to the Yangtze systems. Recreate that with a large, planted, coolwater tank or pond, a soft substrate, and gentle flow. It handles a broad temperature range, from about 14 to 26 C, with a near-neutral pH between 6.5 and 7.8. Room to grow and a seasonal cool spell suit this outsized bitterling.

Good to know

Acheilognathus macropterus is the largest of the bitterlings, a member of the family Acheilognathidae that can exceed 25 centimeters and reach about 27. The name macropterus means large-finned, for the extended dorsal fin of breeding males, which also flush violet and rose. Like all bitterlings it spawns inside living freshwater mussels, which makes aquarium breeding hard.

Did you know

Most bitterlings are palm-sized fish under 10 centimeters, but this one is the giant of the group, reaching around 27 centimeters, larger than many of the barbs and minnows it is related to.

Tank mates

Rainbow bitterling is a mostly peaceful, schooling species that keeps to the middle. These picks match on water type, temperature, pH, size and temperament.