Swan mussel (Anodonta cygnea) care guide

Group
Other invertebrates
Other names
Anodonta cygnaea, Pond mussel
Family
Unionidae
Origin
Europe and Siberia, including Britain and Ireland, south into north Africa; rivers and lakes
Water
freshwater
Maximum size
20 cm
Care level
expert
Flow
Gentle to moderate, food-rich water

Care

The swan mussel is a large freshwater mussel with a thin, rather flat shell 10–20 cm long, usually pale green or brown. It is larger than the duck mussel (Anodonta anatina), with straighter, more parallel upper and lower edges. It lives in rivers and lakes, and because its shape varies so much it has collected over 500 synonyms. Native species: it is native to Britain, needs a coldwater (unheated) aquarium or pond and should not be collected from the wild where that is not allowed. It is declining and protected in several European countries. Feeding guide: as a filter feeder it is very hard to keep fed in an aquarium and usually starves slowly. It is better suited to a large, mature, well-planted wildlife pond with a deep, soft bed of sand or mud to bury in, where it can filter natural plankton. A dead mussel rots quickly and can pollute small ponds or tanks, so check on it. It does not clear green water in a filtered pond to any useful degree. Copper: copper-based medicines and some plant fertilisers are toxic to shrimp, snails and most other invertebrates. Never dose them in a tank holding this animal, and check the label of any treatment or fertiliser before use. Sources: Wikipedia (en.wikipedia.org/wiki/Anodontacygnea). Checked October 2026.

Diet

Filter feeder on phytoplankton, bacteria and fine organic particles. In tanks it needs liquid filter-feeder foods or green water, which is hard to supply without fouling the water.

Breeding

In unionid mussels like this one, females brood larvae (glochidia) in their gills; these are released and must clamp on to a host fish for some weeks before dropping off as tiny mussels. A wildlife pond with native fish can allow this; it is not achieved in home aquaria. Our source does not describe its breeding.

Compatibility and tank mates

Harmless to plants and other animals. Its larvae (glochidia) briefly attach to fish gills and fins as a natural part of its life cycle, which healthy fish tolerate. Keep away from fish that dig or nip the foot, and from crayfish.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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