I don't remember the brand but we used salmon oil for one of our beagles. She had dry, itchy skin before we used it. Food makes a big difference too, she was on Science Diet when we rescued her - she smelled terrible and was itchy. Switched her to Fromm food and she looked and felt great.
I was at the vet the other day and he recommended two fish oil tablets/capsules a day for Obi (just as a general thing for good coat and overall health). We feed Obi a 100g tin of sardines a day but the vet said that he'd need to eat a lot more sardines than that to get the equivalent of a couple of capsules