I’ve found Dogsnaturally to have become very focused on sales to the detriment of maintaining a balanced view, ie biased to make sales. I can’t blame them for the commercial focus, but you need to be aware of that when reading their articles.
I am not keen on supplements because they’re not strictly governed and you’re never sure what you’re actually buying. For fish oil, I prefer feeding Snowie a pilchard every day or so. It’s less processed than a capsule filled with oil. And I do wonder what the extra processing to extract the oil and get it into the capsule does to the oil.