Stoneflies
Gammarids
The upper river runs glacially milky for most of the season, so it's the middle and lower reaches that fish properly — from about Sallanches down, where tributaries from the Giffre and the Bon Nant dilute the glacier-flour and the water clears enough to let you see your fly. Wild brown trout, mostly modest but with the occasional surprising fish from the deeper valley slips that remind you this was once serious water. Alpine tactics: heavy nymph through the pocket water, short-line approach, a willingness to move constantly. The river is spate-responsive and can carry colour for days after heavy rain or a warm afternoon on the glaciers. Prime window is June through September — the glaciers dictate rather than the calendar. Not an easy river, but one of the most atmospheric in the French Alps if you're willing to work out its timing.
- Mixed