Well, if you are going to eat something in the naked then you want it fresh. Which means sashimi and sushi (that has a raw element) should be consumed within minutes of death and in some cases the cause of death to get the best flavor.
You don't know what you are missing if you haven't been salt water fishing and caught a tuna. Then proceed to cut it up and eat it raw, right on the spot. That is the best sashimi.