Whenever possible, you should buy fish that’s wild-caught instead of farmed. According to data from the U.S. Department of Agriculture, farmed fish are clearly inferior to their wild counterparts from both a nutritional and environmental perspective:
Farm-raised fish contain much higher amounts of pro-inflammatory omega-6 fats than wild fish.
Farmed fish are typically raised in crowded commercial tanks and pens and are, therefore, prone to disease and parasites. Fish farmers add antibiotics and pesticides to their food, and even vaccinate them!
Farmed fish contain less beneficial omega-3 fats than wild fish but have a much higher fat content by weight.
Farmed fish meat contains far higher concentrations of dangerous chemicals like polychlorinated biphenyls (PCBs) and dioxins.
Farmed salmon are fed a pink-colored dye to change the color of their flesh.
Fish farming can have drastic effects on wild fish — 95 percent of wild fish will die if they contact water infested with a fish farm’s sea lice.
Wild salmon have an average of 20 percent more protein than farmed salmon — they’re not artificially fattened like farmed salmon.
You can drastically reduce some of the contaminants in fish by cutting off the skin and fat before cooking. Broil or grill fish on a rack so the fat drips off the fish, and don’t use fish drippings for sauces. Don’t eat fish organs or the dark patches of fish meat, because more contaminants collect there.
To reduce the consumption of mercury in fish, avoid eating large predatory fish like shark, swordfish, or king mackerel. White tuna (larger fish) generally has more mercury than light tuna, although levels vary widely.