Respuesta :

Because fish usually has worms in it that can cause diseases so in order to kill/take away the worms you haft to cook it or you haft to take them out of the fish or else the worms could go to your gut and be deadly so that's why cooks are so careful with uncooked fish such as sushi.
Hello ChizzyEze!

We cook fish because it's a source of food! (I don't eat fish, I dunno why I put "We"! LOL)

Have an awesome day! Stay positive! -Wajiha