Preheat oven to 350°F/175°C. Spray two 9x5 loaf pans with cooking spray.
In a large bowl, mix together dry cake mix and dry instant pudding mix. Remove 2 tablespoons of this dry mixture and add it to a bowl with the blueberries. Toss to coat and set aside.
Add the water, eggs, and melted butter (or oil) to the dry mix and combine until incorporated. Gently fold in the coated blueberries. Do not over mix.
Pour batter into prepared loaf pans and bake for 40-50 minutes or until a toothpick inserted in center comes out clean.