Although I am not an avid fisherman, I do live in the land of 10,000 lakes and I have learned the art of filleting (pronounced fil-LAY-ing) fish, and I have discussed it with other fishermen. (It is, after all, a skill that must be taught.) I even own a filleting knife, with a long, narrow, slightly curved blade. And I have never heard anyone in Minnesota or Wisconsin pronounce it FILL-et-ing.