There are several different types of salmon. The 2 major categories are Atlantic salmon and Pacific salmon. There are 2 types of Atlantic salmon and 5 types of Pacific salmon. Atlantic salmon are almost universally farmed now because of declining populations in the wild. Unfortunately, farmed fish have a lot of toxins and contaminants caused by everything from commercial pollution to medicated feeds. And the taste of farmed salmon is pretty bland. The healthiest salmon is wild caught Pacific salmon which includes Chum, Coho (or silver) salmon, chinook (or king) salmon, Pink salmon, and Sockeye (or red) salmon.