Ist the color one of the simanim? There are no fins or scales on the fillet.
Wrong.
1. The fillet sold by Jetro/Restaurant Depot comes WITH scales. AFAIK that's sufficient.
2. Paging
@TimT we've discussed the color issue at length a while ago on the Kashrush master thread IINM, and after reading the sources quoted there, it does seem like the color is a siman muvhak. There's only one non-kosher fish (can't recall what it is at the moment) that could get that color, but that fish is naturally larger, and at the size of salmon would not be edible (or commercially viable).