Season the catfish filets with Old Bay, then dredge in flour, shaking off excess.
Whisk together the eggs and milk in one large (filet-accommodating) dish. Crush the chips in the bag with your hands until about the size of corn-flakes and spread them in another dish. Dip floured filets in egg wash, then in chips, pressing chips all over the filet.
Heat the oil in a deep pot. When the oil is hot enough that a little pinch of flour or a piece of chip sizzle vigorously when dropped in, it's ready. Ease a filet in, and fry each filet about 6-7 minutes total, turning once in the middle, using a couple of wide spatulas.
Remove from the oil and drain on paper towels. Place one large filet on each bun with a really healthy dollop of slaw. Recipe follows.