Cooking food in the wilderness is a time-consuming process. You have to catch or trap your meal, gut and debone it, prepare a fire, and wait for your food to be ready. However, we all know nobody has time for that, so why not just eat it raw? Animals do it, so it must be fine, right? The raw and natural diet is all the rage these days, anyway.
Here's a video that shows how a real hardcore survivalist enjoys eating a fish for dinner:
In case you couldn't tell, this video was satire, meant to poke fun at celebrity survivalists who eat raw fish in “extreme scenarios”. Unlike sushi or other forms of carefully prepared and inspected raw fish, biting into a whole fish can get you seriously ill, or just make you puke your guts out. Unless you want to contract some nasty parasitic worms and/or look like Gollum from Lord of the Rings, there are more civilized ways to process fish in a survival situation.
To reiterate: never eat raw unprepared fish in the wild. One way or another, you will probably end up regretting it. It's not worth the risk of illness—just make a fire and cook your catch like a civilized human. Speaking of which, here's one way to correctly process and cook a fish over a campfire:
The host uses a small metal grill, but you can also cook your fish on a flat rock if no grill is available. It's really not that hard, and this small amount of added effort up front can save you days or weeks of pain and suffering in the long run. Don't eat raw fish or believe everything you see on TV—food should be cooked whenever possible.