Keep everything cold for max crunch: use chilled beer and mix the batter just before frying. If the batter feels too thick, whisk in a splash more beer; if too thin, dust in a teaspoon of flour. Maintain the oil at 350°F—too cool and the coating absorbs oil; too hot and it darkens before the fish cooks. For a non-alcoholic swap, use very cold club soda. Best enjoyed fresh; to re-crisp leftovers, heat in a 400°F oven or air fryer for 5–8 minutes.