An Etymological Dictionary of the German Language/Annotated/Aalraupe
Aalraupe, feminine, ‘eel-pout' (also called Aalquappe, see Quappe), an eel-like fish, originally called Raupe merely; in Middle High German rū̆ppe, Old High German rûppa; as the Middle High German rutte (the equivalent and parallel form) indicates, the base of the word is probably supplied by the Latin rubêta, from which, through the Teutonic custom of displacing the accent in borrowed words (see Abt), we get rúbeta, and then, by the assimilation of the consonants through syncope of the intermediate e, the forms mentioned; names of fishes borrowed in Old High German from Latin rarely occur. See Quappe.