Fresh sockeye salmon. You may think that all salmon is the same, but each of the five species has its own flavor and nutritional makeup. Sockeye salmon, with its firm flesh and rich flavor, is considered a favorite among salmon eaters. Keta salmon, also called chum or dog salmon, is a drier fillet because of its lower fat content and is one of the lesser-known salmon species. Knowing the nutritional differences between keta and sockeye salmon might help you determine which fish is a better fit for your diet.