An Etymological Dictionary of the German Language/Annotated/Forelle
Forelle, feminine, ‘trout,’ with a foreign accent, for the genuine dialectal (Franconian) fórelle, still existing; diminutive of an older Forene (whence *Forenle, Forelle); compare Middle High German fórelle, fórle, forhen, forhe, feminine, ‘trout,’ Old High German forhana, feminine, ‘trout’; compare also Old Low German forna, furnie, Anglo-Saxon fôrne. Probably not from Föhre, Old High German foraha, ‘the fish living near firs, in the brooks of fir forests.’ It is probably connected with the Aryan adjectives in the cognate languages, meaning ‘spotted, speckled.’ Teutonic forhana, from pre-Teutonic prknâ; compare Sanscrit pṛ́çni, ‘speckled,’ and Greek περκνός, ‘livid, dusky’ (πέρκη, ‘perch’).