I've caught 40lb + fish quite a few times at Marshall Creek on threadfin, usually I use whatever I can catch. If you catch a bunch of threadfin where you are fishing then I'd bet that the catfish are feeding on them if they are in the area. Always prefer to catch big gizzards but I'll use either to keep me fishin.
Heck you can usually catch some big carp in the back end of coves spawning about this time of year, they'll be real shallow. Big Carp = Real big minnow!