The most popular way of arguing that fish oil will prevent heart disease is to show that it lowers blood lipids, continuing the old approach of the American Heart Association's "heart protective diet." Unfortunately for that argument, it's now known that the triglycerides in the blood are decreased because of the fish oil's toxic effects on the liver (Hagve and Christophersen, 1988; Ritskes-Hoitinga, et al., 1998)."
It nowhere says the effects were "toxic". It says omega-3 "probably" has depressing effect on VLDL secretion and triglyceride synthesis. On top of it, it was an experiment conducted on rats.
It is difficult to buy the argument that fish oil is liver-toxic, as mentioned in the article.