A short, steep Cares tributary draining the eastern flank of the Picos de Europa and joining the parent river at Las Arenas de Cabrales. The Casaño is alpine in every sense — gin-clear limestone water, plunge pools and pocket water, the smell of wet rock and beech in the high meadows above Asiego. Wild brown trout only, often small but in remarkable numbers in the upper river. Spates short and sharp: three-hour response. Best fished from late May once the snowmelt has dropped back, through to mid-July when low summer water tightens the fishing right down. A river to walk hard on, fishing single careful casts to spotted fish.
- Limestone