I've never seen a difference with fish oil (or any vitamin supplements, etc.). The only thing that ever makes me feel my vits are working is that I have enough ADEK in my blood samples when they test them.
As for fish oil, I've been on it for months and can't tell a difference, but know its good for my heart so will keep taking it. <img src="i/expressions/face-icon-small-smile.gif" border="0">