In medium bowl, mix flour, beer, chili powder and salt with whisk or fork until smooth. Cut fish fillets into 1 1/2-inch cubes. Dip cubes into batter; let excess drip off. Fry fish in batches 3 to 4 minutes, stirring occasionally, until golden brown and cooked through. Drain on paper towel-lined cookie sheet. Keep warm while frying remaining fish.