E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
is the Latin troct-a, from the Greek trokts, the greedy fish (trogo, to eat). The trout is very voracious, and will devour any kind of animal food.
[Roland] was engaged in a keen and animated discussion about Lochleven trout and sea trout, and river trout, and bull trout, and char which never rise to the fly, and par which some suppose [to be] infant salmon, and herlings which frequent the Nith, and vendisses which are only found in the castle loch of Lochmaben.Sir W. Scott: The Abbot, chap. xxii.