Crayfish of all colors sail in our rivers. Only the white-legged crayfish is endemic. The others were introduced by fishing federations, fish farmers, aquarists.
The blue crab of the canyons came from Turkey while traveling in the ballasts of ships. Very aggressive, it colonized the rivers of the south of France and it destroyed the populations of crayfish with white legs. The latter have blue eyes when juvenile and they are very sensitive to asphalting of roads and oil pollution.
The gammares are small freshwater shrimps that give the pink flesh of wild trout.