European bitterling
Rhodeus amarus
The European bitterling (Rhodeus amarus) is a small freshwater fish belonging to the carp family (Cyprinidae), native to Europe and parts of Asia. It typically grows between 5–9 cm in length. Its most remarkable feature is its unique reproductive strategy: the female uses a long ovipositor to lay eggs inside a living freshwater mussel, where the larvae develop safely. The species inhabits calm waters such as oxbow lakes, ponds, slow-flowing rivers, and lakes with sandy or muddy bottoms. Bitterlings are closely dependent on freshwater mussels for reproduction, making them sensitive to environmental changes. In several countries, including Poland, the species is under partial legal protection.
Minimum size: 5 cm
Protection from: January
Protection to: December
