Heat oil in deep-fryer to 325 degrees F (165 degrees C).
Whisk together the flour, cornmeal, garlic salt, garlic powder, and cinnamon in a large bowl. Mix in beer until no dry lumps remain. Dip the cod into the batter, allow some of the excess to run off, then carefully place into the deep-fryer. Cook until golden brown and crispy on the outside, and the fish is easily flaked, about 8 minutes. Cook the fish in several batches to avoid over loading the deep fryer.
