Head to head
European Bitterling vs Sunbleak
European Bitterling
VS Sunbleak
The European bitterling and the sunbleak are two of the smallest carp relatives in Europe, and both have found unusual ways of protecting their eggs.
| European Bitterling | Sunbleak | |
|---|---|---|
| Scientific name | Rhodeus amarus | Leucaspius delineatus |
| Relationship | A small fellow member of the carp family | A small fellow member of the carp family |
| Size and shape | A small, deep-bodied fish, usually only 5 to 8 cm long | A very small, slim, silvery fish, usually only 5 to 8 cm long, with an upturned mouth |
| Egg-laying | The female grows a long egg-laying tube and places her eggs inside the gills of a freshwater mussel | The female lays her eggs in a spiral string around a reed stem or twig |
| Parental care | The male defends a patch of bottom around a mussel and releases his sperm near its breathing siphon | The male guards the string of eggs until they hatch, which is unusual among carp relatives |
| Diet | Algae, plant material, and small invertebrates such as insect larvae and crustaceans | Zooplankton, small insects, and algae near the surface |
| Dependence | Can only breed where suitable freshwater mussels live, so it is vulnerable to anything that harms the mussels | Does not depend on another species to breed, and spreads easily to new ponds |
| Conservation status | Least Concern, widespread across a large range in central and eastern Europe | Least Concern in its native waters, and an invasive species in Britain, where it was introduced in the 1980s |
European Bitterling vs Sunbleak: common questions
Why does the bitterling need mussels?
The female lays her eggs inside the gills of a freshwater mussel, which shelters the eggs and young fish while they develop.
How does the sunbleak protect its eggs?
The female wraps them in a spiral string around a reed stem or twig, and the male guards them until they hatch.
Which one is invasive in Britain?
The sunbleak, which was accidentally introduced in the 1980s, probably with other fish, and has since spread across parts of England.