* Fish oil has been consumed for centuries: People have consumed fish and fish products for sustenance and health benefits for millennia.
* The isolation of specific components is relatively new: The isolation and identification of specific beneficial components in fish oil, like omega-3 fatty acids (EPA and DHA), occurred in the 20th century.
* Modern fish oil supplements: The development of refined fish oil supplements for specific health purposes began in the late 20th century.
So, while fish oil itself has been around for ages, its modern-day use as a targeted dietary supplement is a more recent development.