I lived in Korea for almost two years and regret not eating more fish and other seafood while being there. I'm not sure why the book says not to eat Asian caught fish, but I know that in places such as the Mekong Delta, where it is quite polluted, fish may be contaminated, thus the warning.
I see that you're located in Japan. Aside from being a bit concerned about radiation from the quake a couple years ago, I wouldn't worry about fish in Japan. In fact, I'd be gobbling down some sort of fish, mussel, seaweed, urchin, etc.... every day. Why not? Get that iodine and protein. Get those Omega-3's up and running. Throw in some rice if you can handle it and you're in an optimal Primal zone.
I'm quite envious now.