This is absolutely unreal.

I'll admit I didn't eat sushi until about two years ago when my wife got me into it.  I enjoy it now, but I don't think I could ever have the fish I'm eating staring back at me, regardless of whether or not it was still trying to jump off the plate.

Apparently there is a scientific explanation, if you want a spoiler:

According to National Public Radio, since the fish was killed so recently before serving, the muscle cells were still operational. When the salt in the soy sauce came in contact with the muscle, it triggered a reaction. The fish wasn't necessarily "alive", but the muscles were still reacting like a chicken with its head cut off.