I'm probably bringing them up from 25-30 feet of water and release anything over 10lbs because they're too much of hassle to clean when they get that big. And really I mostly just target them for the sport and the novelty of catching 30+lb fish. They swim off well enough under their own power, but reading stuff about how bass have hard times from that depth, it got me thinking. 

20-30 feet isn't really that deep and they should be fine. You can always bring them up slowly to give them the chance to "burp", but I doubt it's necessary at those depths. 

From my experience, catfish are very hardy fish.

The James river produces some big cats at depth and never heard of any precautions being necessary......good for asking though. 

A guy I watch on YouTube pulls them up from up to 90 feet, they just burp bubbles and seem A- ok