It entirely depends on the conditions, they are kept moist, in the sun, at temperature, many other things. Catfish has the ability, at least on a temporary level, to hold water in its mouth and suck air through the water, so it kind of makes its own bubble. The longest catfish I’ve seen live out of the water has been overnight (about 8 or 9 hours) in a damp burlap bag at about 60-65 degrees.