Gammarids
A central Cantabrian tributary of the Pas, joining the parent river near Sarón. The Pisueña is often the cleaner and steadier half of the Pas system — narrower, more wooded, mixed limestone-and-sandstone bedrock, with classic pool-riffle-glide structure on the middle reaches around Villacarriedo and Selaya. Wild brown trout dominate; sea trout appear in the lower river within the legal calendar. Two SAIH stations (Puente del Diablo and La Penilla) frame the middle/lower stretches, so spate response is well constrained. Worth knowing for the days when the main Pas is too coloured or too low — the Pisueña often holds a fishable window when the Pas does not.
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