Cut the cod into small pieces and skewer. (Fish should not be wider than an inch, or longer than 3 inches).
Put oil in pan over med-high heat.
Mix the flour, corn starch, salt & paprika together, then add milk and whisk well.
Spread some hash browns on a plate, and keep bag out next to it.
Dunk the fish into the batter and coat well. Let excess drip off than place in hash browns.
Sprinkle more hash browns on top of fish, and gently press to adhere. Make sure there are plenty of potatoes sticking to fish. Repeat until all fish is coated.
Once a piece of potato sizzles and quickly floats to the top the oil is ready.
Fry the fish in a few batches, until golden brown and crunchy.
Place on paper towels to drain and cool a little before serving.