When you prepare salmon, you might notice a brown or grayish layer just beneath the skin. This layer is known as the salmon’s fat line or lateral line.
Fat Layer: This is a layer of fat that lies between the skin and the flesh of the salmon. It’s more prominent in wild-caught salmon, which generally have a higher fat content due to their diet and lifestyle.
Muscle Line: This grayish-brown layer also includes muscle fibers that are darker due to the higher concentration of myoglobin, a protein that stores oxygen, in these tissues. This part of the salmon muscle is often more flavorful but has a different texture compared to the rest of the fillet.
Is It Safe to Eat? Yes, the brown or gray layer is safe to eat. It’s just a natural part of the fish, and some people actually enjoy its richer flavor.
However, the texture can be slightly different—often a bit more firm or even tougher—so it’s sometimes trimmed away before cooking, depending on personal preference.
Should You Remove It? – Flavor Preference: Some people find the taste of the fat line to be a bit stronger or "fishier" than the rest of the fillet. If you prefer a milder flavor, you can trim it off before cooking.
Presentation: For a more aesthetically pleasing presentation, especially in dishes where appearance matters, removing the gray layer can make the fillet look cleaner.
In summary, the brown or gray layer on salmon is completely edible and is just a normal part of the fish. Whether you leave it on or trim it off is entirely up to your taste and presentation preferences.