okay, let's do fact & fiction.
most fish have scales; you peel the scales off, cook the fish with or without the skin layer.
catfish do not have scales. they have a slimy skin. it does not cook well. hence the theory of skinning the fish. a good one, imho. it may be imho, but I've met a few catfish on the line and plate.
eel has a similar issue. eel is quite tasty. it's also quite slimy when caught. if you can't deal with the slime, you're unlikely to deal with the thyme, regards eels.
so, anyway.... skinning a catfish is not altogether a simple exercise. you slit the belly, then grab the flaps with pliers and pull off the skin. afixing the head firmly to "something" is a good approach - now driving a nail through the fish's head while it's alive vs dead is an ethics issue vs a effective mechanical issue.
whether you prefer to have the fish slowly die flopping around in air or die quickly by a nail through the brain, your choice.