As we're talking about serious (though not entirely un-ludicrous) experiments concerning dead fish, I'm not going to miss an opportunity to post this video of a dead fish placed in "fast flowing water" (it's actually a tank with a jet and an outlet, but the effect is much the same).

Which way do you think the dead fish will move, upstream or downstream? Place your bets now.

https://vimeo.com/44887922