finnock
A young sea trout, in the year after they return to fresh water after their smolt migration stage.
Previous to their descent, I caught in all, not far from the tideway, about half-a-dozen finnocks, on two or three different occasions.
Where it comes from
A possible anglicisation of Scottish Gaelic fionnag (“young salmon”). Compare fionnag (“whiting”), a calque of English whiting, from fionn (“white”).
Adapted from the Wiktionary entry finnock (CC BY-SA 4.0).