fishy (adj.)youdaoicibaDictYouDict[fishy 词源字典]
late 15c., "fish-like, slimy," from fish (n.) + -y (2). In reference to taste, from 1540s. Sense of "shady, questionable" is first recorded 1840, perhaps from the notion of "slipperiness," or of giving off a bad odor.[fishy etymology, fishy origin, 英语词源]