In the great scheme of things, the fish knew it fucked up bigly in the previous life to be born as a fish. It's like a football team getting relegated several divisions down instantly. The fish has to suffer such tribulations, the animal rights activists and PETA nutjobs don't get it.
Even if it wasn't eaten by humans, it would most definitely become food for another predator out in the wild. It's just a phase, a cosmic lesson.