Please allow me to quote a passage from an article https://time.com/6199237/is-farmed-salmon-healthy-sustainabl...

> We know that every fish is a trade-off between omega-3 content and toxic content like PCBs. From the perspective of salmon in general, the balance favors consumption of that fish. Now the challenge here is that I can’t tell which salmon is farmed the right way or the wrong way.