All fish / Acheilognathidae

Amur Bitterling

Rhodeus sericeus

Also known as bitterling, amur bitterling, rhodeus sericeus amarus, european bitterling, タナゴ, 黑龙江鳑鲏, 鳑鲏

A small, deep-bodied silvery cyprinid with a turquoise stripe along the rear of the body; breeding males turn pink to red with bright eyes. People keep it in cool-water aquariums and wildlife ponds for its colour and its unusual way of breeding inside freshwater mussels.

Care at a glance

Care level

Moderate

Temperament

Peaceful

Adult size

6 cm

Temperature

5 to 22 °C

pH

6.5 to 8

Smallest tank

80 litres

Keep as

Group of 6 or more, ideally with more females than males

Diet

Omnivore: small live and frozen foods such as bloodworm and daphnia, quality flakes and some plant matter

Swims

Middle of the tank

Lifespan

3 to 5 years

Water

Freshwater

Wild range

Amur River basin in eastern Russia, northeast China and Mongolia

Breeding

The female uses a long ovipositor to lay eggs inside the gills of a live freshwater mussel, and the male fertilises them by releasing sperm near the mussel's inhalant siphon. Spawning in captivity is possible if healthy mussels and a seasonal temperature cycle are provided, but keeping the mussels alive long term is the hard part.

Good to know

This is a coldwater fish that does poorly kept warm for long periods; a winter cool-down helps. The European bitterling (Rhodeus amarus) was once treated as a subspecies and looks very similar, and some countries limit moving or releasing bitterlings.