I had an injured guppy "disappear" in a few minutes. I knew it was somewhere in the tank, but couldn't find it. Although I did not take everything out to find it.
I also recently lost my blue german ram. One night he was hanging at the surface, but I had raised the CO2 too high so I thought that's what was stressing him. Next morning, no trace of him.
I also lost a microrasbora. I always try to count, but they're very small. Finally, I realized that I had one less than before. I have no idea what happened.
I've lost ottos, guppies, pygmy cories and probably some amanos and RCS along the way. I know the fish and inverts in the tank are eating the remains. But the tanks have so many fish, inverts and plants that I can't find the dead bodies before the fish clean them up. That's just part of their life cycle. This is one reason why I try to remove any sick fish the very instant I see it. Because if that fish dies, I know the others will feast on it, possibly becoming infected with whatever got the first fish.
I also just find it hard to count fish when I have a school of them. My dwarf chain loaches move so fast, I can never tell how many I have. And try counting 39 amanos in a planted 75g tank? No way! Who knows how many are in there now.
In all cases, my tanks have closed lids with my 75g having a canopy in addition to the glass lids. So the fish aren't jumping out. Nature is just doing what nature does.
I'm sorry you lost your catfish.
But maybe you'll get lucky and find it alive and well in a few days. I've seen posts on here before with people having lost various fish, mostly catfish and plecos, even after tearing up their tanks, trying to find them, only to find absolutely no sign of them. And then a few days later, they either turn up dead on the floor or alive and well in the tank. It's amazing how well some fish can hide.