Pat the fish fillets dry with paper towels. Cut the fillets into even portions if they are large.

In a mixing bowl, whisk together the flour, cornstarch, baking powder, salt, pepper, garlic powder, and paprika. Slowly pour in the cold sparkling water while whisking until a smooth batter forms.

Lightly dredge each fish fillet in a little extra flour, shaking off any excess. Dip the fillets into the batter, ensuring they’re fully coated.

Preheat the air fryer to 400°F (200°C). Spray the basket with cooking spray. Place the battered fish in a single layer, leaving space between each piece. Spray the tops lightly with cooking spray.

Cook for 10–12 minutes, flipping halfway through, until golden brown and crisp. Remove the fish carefully and serve immediately.