Step 2: Cut from the anus up the middle of the belly to the "V" right behind where the gills come together (about where my left hand is in this picture). A sharp knife of any size will do the trick--you just need to cut through the skin and muscle.
Step 3: Between the jaw and the gills are two soft spots that form a V under the chin. Stick the knife in one side and out the other and cut up so it looks like this:Step 4: Using the hole you just made, grab the jaw in one hand and the lower gill section in the other and pull apart.Step 5: Keep pulling. This will tear off the first pair of bottom fins and pull all the entrails out in one motion.
Last, rinse the inside and outside of the fish and scrape along the inside spine with a fingernail or something else hard and blunt to scrape the majority of the black gunk out. If you are doing this at the river you'll need to wash the fish inside and out again before cooking it when you get to clean water.
At this point, I just cut off the head and cook it with the skin, fins, tail still attached. Season the inside of the fish and then either flour/cornmeal the outside and fry it OR wrap it in tinfoil and bake or barbeque it. Once it is cooked the fins pull out easily taking their bones with them and the meat easily separates from the skeleton of the fish as well--lay the fish on your plate, lift the spine at the neck and tap the meat down with a fork working from the neck to the tail, flip over and repeat. Yummy! I'll have to get some pics of cooked fish and the deboning process when we catch and cook some next . . .
And remember if you've been tossing fish heads into the woods and then decide you need to do some other business out in the same woods, "Check your spot before you squat". ;)