Make sure the skins are fully scaled. Pick off any stray scales. Cut the skins into large pieces.
Bring a medium pot of water to a boil and add a few tablespoons of salt. Bring the water back to a boil after adding the skins and boil them for at least 1 minute, and up to 5 minutes for thick skins like sturgeon or shark. Most fish only need a minute or so.
Remove the skins from the boiling water and lay them, meat side up, on a cutting board. Carefully, using a butter knife, scrape away all the meat and fat from the underside of the skin. This is a gentle process. You might rip the skin a few times, and that's OK. When each skin is clean, lay it on a dehydrator rack.
Dehydrate the skins fully. You can do this at a range of temperatures. I go for about 140°F, but you can go higher or lower. You could also use your oven set on low, especially if it is a convection oven.
When the skins are completely dry, so they snap when bent, you can fry them now or store the skin for a couple days in the fridge; you can also freeze them. Fry at 360°F one or two at a time. They will puff up instantaneously. Fry until the bubbles stop, about 30 seconds.
The moment they come out of the fryer, dust with salt and whatever other seasoning you like. I love using Mexican Tajin.