There's a lot of content in this article but for my money they've buried the lede.

> Even more startling results were obtained with experiments with a dead trout. It was tethered on a line to an object in flowing water and even though it was dead, it still adopted a swaying movement in the vortex street and was actually drawn upstream!

Vid or a dead fish swimming upstream (not linked in the article!): https://www.youtube.com/watch?v=_ZBWnhzYvts