I've always wondered that myself. It doesnt seem like a natural food, hunting in the wild for fish would indicate that cats like to be around water. Cats don't even like water, do they? What if it's a myth, and they like chicken livers just as much?
Mainly becasue they enjoy the taste. Another reason is because i the wild that is what they usually hunt for in the wild.
welll..its the natural charecteristic of a cat to like fish just as you like your fav dish.....