In reality, it is the guts of fish that rot and stink before the head. Source: https://www.phrases.org.uk/meanings/fish-rot-from-the-head-down.html https://ww

In reality, it is the guts of fish that rot and stink before the head. Source: https://www.phrases.org.uk/meanings/fish-rot-from-the-head-down.html https://www.phrases.org.uk/meanings/fish-rot-from-the-head-d... The guts of fish will start to rot quickly and spread terrible bacteria and disease throughout the entire fish. Source: https://www.reddit.com/r/Survival/comments/mv04em/is_gutting_fish_necessary_what_are_the_reasons/ https://www.reddit.com/r/Survival/comments/mv04em/is_gutting... Hope this helps. I'm not sure why you were downvoted for expressing curiosity about fish biology.