Marine fish are aquatic animals that live in saltwater environments, such as oceans and seas. They are characterized by their gills, which allow them to extract oxygen from water, and their fins, which help them swim. Marine fish come in various shapes, sizes, and colors, and they play essential roles in marine ecosystems. These fish are an important food source for many animals, including marine mammals and birds. They also contribute to the balance of marine life by participating in the food web. Some well-known examples of marine fish include tuna, salmon, and clownfish.