If you go fishing in the Sea of Cortez - whether by dinghy, snorkeling with a speargun,or via the mother ship, chances are you will catch some kind of critter and it'll most likely be yummy. Here's how GB typically processes his catch, using the broad flat space of our forward bow.
We have for today's demonstration a Pacific porgy (top) and a finescale triggerfish (bottom), caught in July 2009 at Puerto Refugio, north end of Isla Angel de la Guarda. Here, GB starts with the triggerfish and fillets the first side. His first cut is behind the dorsal fin, running downward at an angle behind the gill cover toward the the midline and a bit below the level of the pectoral fin, taking care to not cut or puncture the nasty innards in the belly. The angle of this first cut is most visible in the third photo in that row above.
The second cut is along the dorsal spine back toward the tail. The third cut goes downward from in front of the tail toward the belly but stops a bit past the fish's midline - again, this is most visible in the third pic. The last cut runs along the lower midline, roughly parallel to the belly, between aft of the gill cover and forward of the tail. The goal with all these cuts is to harvest as large a fillet as possible while leaving the innards intact so as not to contaminate the edible flesh.
Next, GB flips the fish over to remove the second fillet the same way. Finally, he tosses overboard what's left of the fish - usually, the skin; and the head, spine, innards and tail all in one piece - and I give our thanks to Neptune. Typically the remains are quickly scavenged by seagulls and bullseye pufferfish. Makes you think twice about falling overboard...
Triggerfish have a fairly firm, white-ish flesh that works very well in tacos. If you catch a hogfish with its very white, delicate flesh, you may want to prepare it as you would a fillet of sole. (That's a male hogfish with the teeth and the big forehead bump, in the top of that pic over on the left.) A skipjack's dark-red, almost purple flesh is too heavily oily to be to everyone's liking but it stands up well to assertive flavors like a lime, garlic, onion and soy marinade*, or BBQ smoking; basically approach it as you would beef. A yellowtail jack's, yellowfin tuna's, or dorado's (mahi-mahi's) flesh makes excellent sashimi, sushi, cooked fillets - you name it. That there in the photo on the right is a recently deceased yellowtail jack in the bottom and up along one side of a 5-gallon bucket.
* The Propane Chef recommends that when "cooking" an oily fish like skipjack in lime juice - say, as you would for ceviche - you first cover the fillet with lime juice, let it chemically-cook the fish, then pour off the lime juice and the fish oil the lime juice has drawn out. Next, cover the fish with fresh lime juice, olive oil (to replace the pungent fish-oil flavor with a fruitier, more fragrant oil flavor), your other marinade ingredients, and continue with your recipe.
Fishing is murder. Tasty, tasty murder.