These are companies that most likely molecularly distill their fish oil though

That means they use aging diseased fishes or must obtain fishes from contaiminated waters in order to have to go through that process.

Good fish oil should never be moleculary distilled whatsoever because it changes the molecules of the fish oil and you will never benefit from it if it goes through heavy processing.

Make sure the fish oil is from pristine waters so that it doesn't have to go through a purification process thus maintaining all the benefits that real fish oil should.