Combine water, brown sugar and kosher salt; mix well. Pour into ceramic dish or bowl. Trim catfish fillets to 6-in.-x-1-1/4-in.; reserve trim. Place fillets in brine; marinate for 1 hour. Lay oiled cheesecloth over wire rack. Fold each fillet in half, skin side out; place on covered rack. Refrigerate uncovered for 1 hour to dry fillets. Smoke fillets until light brown; finish in moderate oven. Fish should flake easily when cooked.