Pretty simple. The main thing is you have to hang them and cut the tails off and let them completely bleed out. Doesn't matter how big or what kind of catfish. I carry a pair of loppers in my boat and with the fish still on the stringer, I put them in a plastic tub and cut all the tails off then hang them over the side of the boat until they bleed out usually 20 to 30 min. Put them back in the tub and fillet them out and trim all red meat off. Some people trim the belly meat but I stay away from it. One bite of belly fat will be all you want. Put it in ziplock bags and keep it in the ice chest until I get home then wash it off a little before freezing it. You don't want to wash all the oil off because that's where you get the flavor. Most people over wash the fish. I use Cuda fillet knives with 7 and 9 in blades. I don't use electric knives on catfish. Wash it up a little bit and make sure to trim off all red meat. If it's bled out good the meat should be almost white. Roll it in a Cajun batter and it is unreal.