Au fil du Doubs, Stage 3/4Fishermen are often met along the path. The Doubs has a unique fish population including the authentic Doubs trout with black stripes, barbel, grayling, pike and of course the elusive apron, also known as Roi du Doubs.learn more on schweizmobil.ch13.0 km|200 m|220 m|3h 20m