Excellent post and I’ll add that this switch was known decades ago. I was taught about it in ag school in the 70’s.
My primary fish is canned, wild salmon, which is a great source of Omega-3. It has the great benefit of also being one of the cheapest fish products, and, having eaten it all my life, it’s one of my favorites.
And in at least a partial recognition of the importance of Omega-6/Omega-3 ratios, the American Heart Association says eating salmon, or some other oily fish is beneficial to the heart. And, fish oil has become a supplement that most all doctors now seem to consider beneficial.
You’re right, it has been known for years that grain feed shifts the ratio of Omega-6 and Omega-3 in food animals and eggs. One of the first big observations (1950s and ‘60s) on the importance of Omega-3 was that Eskimos, with their super high fat diet, had almost no heart disease due to the amount of wild fish in their diets.