Why do food fish sometimes have a strong odor?

Many are named after animals including - alligator, bird, boar, buffalo, cat, cow, dog, elephant, frog, goat, goose, hawk, horse, eagle, leopard, lizard, parrot, porcupine, rabbit, sheep, pig, squirrel, hog, tiger, toad, unicorn, viper, wolf, scorpion, zebra, robin, and raven.