I don't know about salmon in particular but with my poodle, fish or cod oil capsules - and this is a while ago! - worked wonders with his coat. Of course, he also did eat the real thing - salmon - and I think the real thing trumps the capsules every time!!!! (Unless there is some medical reason a dog/cat/bunny.person cannot digest the fish).
Of course, feeding the real fish means deboning and that takes time!
"There are two means of refuge from the miseries of life: music and cats" Albert Schweitzer