No offense to others' cultural preferences, but my childhood orientation toward Christmas was colored so heavily by 1) our German-Mennonite background which manifested itself mainly in Christmas baked goods and 2) perhaps more importantly, the pop-culture ubiquity of Dickensian/Victorian Christmas imagery, that fish at Christmas just seems
wrong, like a vegetarian 4th of July or an ascetic Valentine's Day ("Honey, as a sign of my love for you, I've bought you this heart-shaped box of buckwheat groats, and I got a babysitter so we can spend the whole evening meditating").
You need spend no effort attempting to convince me of the theological and cultural appropriateness of fish at Christmastime; I know all that, I recognize that this is merely my prejudice, born of growing up in a place where the indigenous fish are rectangular and live their lives in beds of bread crumbs at the bottom of the sea. Nevertheless, for me Christmas is only for large roasted meats and birds, massive tubs of potatoes and stuffings, rolls and Jello-mold salads and many, many desserts. Fish, even bought at Fox & Obel on Christmas Eve, is reserved for today, the first day of repairing the damage wrought by a month or more of fatty, Fezziwigian excess.