I believe that the picture was from Peru; I have seen much that I will not repeat here. A very mild taste; more meat than on squirrel, that's for sure.
I was brought up to believe the only thing you leave the head on to cook is trout. Because you never behead the king and trout is the king of fish....(old fisherman's lore, if you cut the head off a trout, you will never catch another one.) I love trout and broil them until the eyes turn white, turn it over and use the eyes to gage doneness. Only takes a few minutes per side. I liked to add lemon juice when broiling.....When younger, I use to love fishing.
My grandfather taught me to fish in Northern Ontario, for perch, pickeral, several types of trout and, wait for it, smallmouth bass. Mmmmmmmm. We threw bluegill on shore because they were considered junk fish.
My grandmother taught me to clean and cook fish (lightly seasoned salt in bacon grease and pan fried). All heads removed. The only heads I have not removed from fish are marlin (on my basement wall) and muskie (unfortunately not).