Trout
late Old English truht, from late Latin tructa, based on Greek trōgein ‘gnaw’.
wiktionary
From Middle English troute, troughte, trught, trouȝt, trouhte, partly from Old English truht(“trout”), and partly from Old French truite; both from Late Latin tructa, perhaps from Ancient Greek τρώκτης(trṓktēs, “nibbler”), from τρώγω(trṓgō, “I gnaw”), from Proto-Indo-European *terh₁-(“to rub, to turn”). The Internet verb sense originated on BBSes of the 1980s, probably from Monty Python's The Fish-Slapping Dance (1972), though that sketch involved a halibut.
etymonline
trout (n.)
Old English truht "trout," in part from Old French truite, both from Late Latin tructa, perhaps from Greek troktes "a kind of sea fish," literally "nibbler," from trogein "to gnaw," from PIE *tro-, from root *tere- (1) "to rub, turn." In late 17c. slang, trusty trout was used in a sense of "confidential friend."
