Peel back corn husk, and remove silk on all 4 ears of corn. Break off corncob at the base, leaving husk attached. With a sharp knife, slice kernels off the cobs of 2 of the ears. Put aside the other 2 ears. Prepare a hot fire.
Fold back a few leaves of each corn husk, and place a catfish fillet in each. Top each fillet with ¼ of the corn kernels, green onions, bell pepper, capers and butter, and top with a sprig of thyme. Season with salt and pepper to taste. Tie husk together with strips of corn husk or kitchen twine (can be done earlier in the day and kept refrigerated until ready to grill).
When ready to grill, place catfish fillets in corn husks on the grill directly over the fire, and grill for 5 minutes. Then move to the indirect side of the grill, and continue to cook for another 6 to 7 minutes with the grill lid closed.
Serve corn husk packets by folding back the top of the corn husk to display the fish inside.
Nutritional Information per serving: calories, 807; protein, 40 g; carbohydrates, 52 g; fiber, 4 g; fat, 50 g; cholesterol, 187 mg; sodium, 1,405 mg.