Caddisflies
Gammarids
Central Cantabria's Pas is a fascinating mixed-geology trout-and-sea-trout river with strong migratory-fish history. Mixed geology (limestone to sandstone) creates diverse habitat and more variable water colour than pure limestone — sometimes advantageous when clarity becomes too high. The 57 km length provides extensive opportunities across distinct sections: rocky upper beats for trout, stronger middle sections that respond well after rain, and slower lower beats with some migratory interest. In modern practical terms this is better treated as a versatile trout river than as a realistic salmon-chasing destination.
In Cantabria's shorter mountain and foothill trout rivers, fish make the most of spring olives and stoneflies in clear windows between freshets, then switch to evening caddis and small buzzers through the warmer months, with terrestrials becoming a key option in sheltered glides and under tree cover once summer settles in.
- Mixed