The bitterling, Rhodeus sericeus, or Amur bitterling is a small fish of the carp family. Mussels form an essential part of its reproductive system, with bitterling eggs being laid inside them.
Long thought to be symbiotic with the mussels (whose larval phase attaches to fish gills during development), recent research has indicated they are in fact parasitic, with co-evolution being seen in Chinese bitterling and mussel species.
Bitterlings usually reside in areas with dense plant growth. They are a hardy fish, and can survive in water that is not very well oxygenated. They grow to be 3-4 in. long at most. The bitterling's diet consists of plant material and small larvae of insects.
Colour VariationThere are 'transparent' scale variants of bitterlings, though not common, if exploited in the aquarium trade.
For photos of transparent variants of bitterlings, please see: http://www.jstage.jst.go.jp/article/zsj/15/3/425/_pdf
bitterling in Bulgarian: Горчивка
bitterling in Czech: Hořavka duhová
bitterling in German: Bitterling
bitterling in French: Bouvière
bitterling in Upper Sorbian: Lěćny hórčink
bitterling in Italian: Rhodeus sericeus
bitterling in Lithuanian: Kartuolė
bitterling in Hungarian: Rhodeus
bitterling in Dutch: Bittervoorn
bitterling in Japanese: タナゴ
bitterling in Polish: Różanka (ryba)
bitterling in Slovak: Lopatka dúhová
bitterling in Slovenian: Pezdirk
bitterling in Turkish: Acı balık