Fatty Layer Under the Skin The brown or gray layer is mostly fat, which is rich in healthy omega-3 fatty acids and helps keep the salmon moist and flavorful during cooking.
Muscle Protein (Myosin) The darker color can also be due to myosin, a protein that exists naturally in fish muscle. This protein is more concentrated in the belly area, where fat is stored.
Flavorful and Nutritious This layer adds richness and flavor to the fish. The healthy fats in the layer provide benefits for heart health and help create a succulent texture when cooked.
Cooking Reaction When cooked, the fat layer melts, making the salmon juicier and tenderer. It also helps the fish retain moisture, preventing it from drying out.
Color Variations The brown or grayish layer can vary in color depending on the fish's diet, how it was raised (wild vs. farmed), and its age. Wild salmon usually has a deeper, richer color.
Avoid Overcooking The fat layer can easily dry out if the salmon is overcooked. To keep it tender, cook the salmon to an internal temperature of 125°F for a perfectly flaky result.
Optional to Remove Some people prefer to remove the brown or gray layer before cooking, but it’s full of flavor and nutrition, so leaving it on can enhance the overall taste and texture of the salmon.