Old fish stinks no matter if its shark, swordfish, mackeral, flounder,,,,,,,anything at all.
Longgggg story made short, I used to grab some of the sharks that the scientists had taken 'what they were studying' out of the animal, and my Bermudian friends would cook it up. It was only dead about 2 hours and it was delicious, but if you leave it to get warm, it will decay really fast, as sharks are full of urea and thats stinky.
Shark has to be cooked right away, not left around like you can do with other fish, ick.
Jane