In a large heavy skillet heat the butter over moderately high heat
until the foam subsides, in it saute the bass, turning it once,
for 1 minute, and transfer it with a slotted spatula to a plate.
Into the butter remaining in the skillet stir the cream, the
Champagne, the Worcestershire sauce, the mustard, the capers, and
salt and pepper to taste, scraping up the brown bits, return the
bass to the skillet, and simmer the mixture for 5 to 7 minutes, or
until the bass just flakes. Serves 4.