Description and characteristics
The grayling (Thymallus thymallus) is a medium-sized salmonid with a fusiform body covered with small scales. It stands out for its large, brightly coloured dorsal fin, resembling a flag. Colouring is grey-olive with silvery flanks.
Habitat and distribution
It prefers clear, cold, oxygen-rich waters with stony or sandy bottoms — Danube branches and tributaries with fast currents. It is sensitive to water quality.
Diet and behaviour
It feeds on aquatic insects, larvae, small crustaceans and occasionally small fish. It hunts actively, preferring insects fallen on the water surface.
Reproduction
Spawning occurs in spring at 6–12°C, with females laying eggs on stony bottoms. The fry grow slowly.
Economic and ecological importance
The grayling has value for sport fishing, being an emblematic fish of clean waters. Ecologically, it is an indicator of water quality.
Threats and conservation
It is strongly affected by pollution, dams and rising water temperatures. Protection of clear waters is essential.
Fishing and legal minimum size
The grayling is caught with a rod and fly. In the table of minimum legal sizes, the grayling (Thymallus thymallus) has a minimum legal size of 25 cm.
Conclusion
The grayling is a demanding salmonid, a symbol of clear, cold waters, important for biodiversity.