Red Velvet Shark Cake

Name: Red Velvet Shark Cake
Ingredients: Flour-based baking spray, for the cake pans; 1 cup (2 sticks) unsalted butter, at room temperature; 3 cups granulated sugar; 4 large eggs; 2 teaspoons vanilla extract; 4 ounces red liquid food coloring; 1/4 cup cocoa powder; 5 cups all-purpose flour; 2 teaspoons baking powder; 2 teaspoons salt; 2 cups buttermilk; 2 teaspoons baking soda; 2 teaspoons white vinegar; 2 pounds (8 sticks) unsalted butter, at room temperature; 4 pounds confectioners' sugar; 1 tablespoon clear vanilla extract; Milk or cream, for thinning; Black gel food coloring; Sky blue gel food coloring; Royal blue gel food coloring; Red gel food coloring; 3/4 cup assorted blue sprinkles; 1 1/4 cups fish-shaped hard candies; 2 white confetti sprinkles; 12 ounces white candy melting wafers