No Natural Process will do this
There is nothing that will make catfish sentient land dwellers in 10,000 years, short of major, sustained human genetic modification towards this goal, from a better understanding of biology than we have. We probably need 50 years to get to this level of understanding.
Here are the issues as I understand them:
1) Fish live in an aquatic environment, which supports their body. Their bones are cartilage, circulatory system and muscles are smaller and weaker than is needed to move on land. Basically, all that has to go. We're looking for a high powered land dwelling musculoskeletal system. This is the big advantage that made whales, dolphins and seals competitive when they returned to the sea. This is a big, brutal fix, and would take a huge number of gene replacements.
2) fish aren't the sharpest tool in the shed, for the most part. 335
Surprisingly, I think this is easier to fix than the previous problem. We have some genes isolated for intelligence, in 50 years I suspect we'll have a decent map of them. Chuck those into some fish, with the right control sequences, and the fish should grow big brains, which, if the other tweeks haven't worked, will rapidly kill them, due to their relatively sluggish metabolism not being able to support the energy demands.
3) You'd be attempting to do this all with genes that work in humans, because we're the only sentient creature we know, so the obvious starting point. We're a massive evolutionary distance from fish, and there's going to be a whole bunch of genes that need something else, that work differently, that do something wholely unexpected. With the current state of biology, I'd assume 2-5 years worth of research for each gene. You're going to be replacing at a bare minimum, a couple of thousand.
It might be easier to give humans a head that looks like a catfish. I don't know how you'd do that either, but it's got to be simpler than trying to circumvent millions of years of evolution.
Note: unless the apocalypse happened thousands of years in the future, this is not "lone mad researcher makes sentient fish" territory. This is a larger undertaking than the moon landings, involving a similar number of people, with technology we don't have yet. 335