Yes! I've been taking fish oil for a while now, off and on (now on). I've read so much about the beneficial properties of fish oil in mental disorders, so it motivates me to try to remember to take it.

It seems like fish oil is a widely recommended part of treatment now -- I've read lots of conventional books on Bipolar that all mention it, along with daily vitamins, as vital to your "brain health".
I'm surprised at your fast reaction, since I've been taking it for a few years now with no really obvious signs that it's working for my mood instability. I might be on a low dose (18% EPA, 12% DHA). I do get lots of small benefits, though, like feeling more awake and clear headed, right after I start taking it.