Preheat oven to 150°F (60°C). In a small bowl, stir together garlic salt and 1/2 teaspoon celery salt. In a deep pan over medium-high heat, heat 2 inches oil to 400°F (205°C). Working in batches, carefully add frozen fries. Cook 3 to 6 minutes until golden brown. Remove with slotted spoon and drain on paper towels. Season to taste with salt mixture. Keep warm, uncovered, in preheated oven.
In a small bowl, beat egg and remaining 1/2 teaspoon celery salt until frothy. Stir in baking mix and ale, taking care not to over stir (batter will be lumpy). Dredge fish pieces in flour. Let sit in flour until ready to use. Bring oil temperature to 375°F (190°C). Re-dredge fish and shake off excess flour. Coat with ale batter and carefully slide into hot oil, working in batches so as not to crowd pan. Fry for 6 minutes; turning occasionally. Drain on paper towels. Serve fish hot with seasoned fries and condiments. Garnish with lemon wedges on the side (optional).