European Grayling

• Its large iridescent dorsal fin serves as a display in courtship.
• Its silvery colouring hides it against the river's gravel bed.
• It lives in fast, cold, well-oxygenated rivers.

Skeleton type

Vertebrate - internal bony skeleton (fish)

Habitat and environment

Fast, cold, well-oxygenated rivers of Europe, from the United Kingdom and France to the Urals in Russia

Birth weight

Egg laid in gravel; a tiny larva on hatching

Size at birth

A tiny larva on hatching; it grows fast, reaching some 20 cm by the end of its first year

Sexual maturity

2-3 years (15-20 cm long), though it may be delayed to the end of the third year depending on the region

Gestation / incubation

Several weeks of egg development in spring

Litter / clutch size

Thousands of eggs per female (no precise figure for fecundity found)

Sources consulted: ScienceDirect (hatchery reproduction study); Animalia.bio; ResearchGate (River Lugg age growth study); PMC (alpine river growth modeling study); FishBase; Grokipedia; PMC (grayling stocking study)

Best time: From March to May, during spawning, over gravel stretches; the rest of the year it is found in cold, clean, well-oxygenated currents.