Red-tail bitterling

Acheilognathus tonkinensis

Also known as Chinese red tail bitterling, Tonkin bitterling

FreshwaterFish

Care at a glance

Temperature: 61–79°F (16–26°C)
pH: 6.5–7.8
Adult size: 4.7 in (12 cm)
Minimum tank: 40 gal (150 L)
Temperament: Mostly peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Medium
Breeding: Hard
Rarity: Rare
Origin: Northern Vietnam and southern China
Family: Acheilognathidae

Overview

The red-tail bitterling is an easygoing, temperate schooler whose males take on warm color as they mature, no heater required. Keep it in a group of six or more; kept together, the males color up and display far more than lone fish do. It swims in the middle of the tank and is extremely gentle with tankmates, so it mixes well with other calm, temperate community fish. Feed it as an omnivore, with small frozen foods, flake, sinking pellets, and some vegetable matter. A planted tank and a cooler season suit it. A group is comfortable in a tank of around 150 liters or more.

In the wild

The red-tail bitterling lives in slow, vegetated streams and backwaters of northern Vietnam and southern China, among plants over soft beds. Recreate that with dense planting, a soft substrate, and gentle flow in a cool or unheated tank. It suits a temperate range, from about 16 to 26 C, with a near-neutral pH between 6.5 and 7.8. A seasonal cool period helps bring breeding fish into condition.

Good to know

Acheilognathus tonkinensis is a deep-bodied bitterling in the family Acheilognathidae, reaching about 12 centimeters. In the breeding season males light up in shifting rainbow colors while females stay plain and grow a long ovipositor tube. With it the female places her eggs inside a living freshwater mussel, where they develop, which is why aquarium breeding is hard.

Did you know

In breeding dress the males shimmer through a range of rainbow colors, earning the fish its other name of Tonkin rainbow bitterling, while the drab females grow a long tube to slip their eggs safely inside a living mussel.

Tank mates

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