Why is salmon so healthy, anyways?
The human body needs fatty acids for thousands of various functions in order to stay alive, and can produce all the unique fatty acids it needs except for two: Omega-3 and Omega-6. We obtain these “essential” fatty acids through the diet, and optimally, in a 2:1 ratio. But that’s not the case with most Americans, as our high consumption of omega-6 foods (vegetable oils and corn) trumps the amount of omega-3 foods in our diet (flaxseeds, grassfed beef, and oily fish like salmon). This long term inflammatory imbalance puts one at risk for chronic illnesses like coronary heart disease and arthritis, hence the push for more salmon on our plates to help us get more of those healthy omega-3's.
Here’s the catch: a salmon gets all of its omega-3 content from its diet of small “feeder” fish, who get their omega-3 content by dining on green algae. This occurs naturally in the world of wild salmon, but the diet for their farm-raised brethren is up to the farmer. Even when fed high-quality omega-3 oil, farm-raised salmon tend to have lower levels of usable omega-3 fats due to their higher total fat content and higher amounts of omega-6 in farm-raised fish negates from their omega-3 stores. The reason behind this comparably high fattiness for farm-raised salmon is due to less physical activity... unlike wild salmon, farmed fish have the luxury of laziness when it comes to feeding and predators, and no one earns a lean swimmer’s body by merely floating around in the water.
A basic proximity rule with organisms is that the more densely they’re packed, the more tendency they have to spread disease and parasites among each other. In fact, this rule applies to humans as much as it applies to salmon. Farm-raised salmon are sometimes distributed medication to quell outbreaks. Concentrated amounts of antibiotics, pesticides, and other substances provided by salmon farmers for disease damage-control doesn’t sit well with a lot of salmon consumers, leaving many to opt for the wild-caught salmon that’s less likely to fall sick in the first place.