In a skillet over medium-high heat, heat the olive oil; cook and stir the garlic in the oil until golden brown, taking care not to burn the garlic. Mix in the tomatoes until they release their juices. Add 1 teaspoon oregano and mix well.

Season the cod and shrimp on top of the tomato mixture. Simmer for 3 minutes, covered. Season the cod again with salt and 1 tablespoon oregano; re-cover and cook for another 3 minutes. Remove the cover and cook for 2 to 3 minutes, or until the juice has slightly evaporated.