Almost all of the channel cat I've caught this year have been caught on 3-4 creek chubs, 2-3 inch bluegill, or 2-3 inch bullhead. The tricky part for me is finding a good spot to catch all of this bait consistently because I'm out fishing for channel cat at least every other day. I actually found a good spot to catch all of my bait about 2 days ago, but it is about 30 miles from where I live. I took an old quart sized ice cream pale and filled it up with chubs, blue gills, and bullheads and used what I needed for bait yesterday, then put the rest in the freezer. As long as you don't freeze, then unfreeze, more than 2-3 times the bait won't get soft on you.
I fish for cat whenever I have the time, but I've definitely found that right before nightfall is when I have the best luck. I do a lot of my fishing near the Cedar River dam in Waverly, IA and the cat move up closer to the dam come nighttime.
I used an Abu Garcia spin cast reel with a 6 and 1/2 foot medium action rod with 12 lb test Stren "super knot" line. I like to use the 2/0 size Octopus Circle hooks with a 1/2 ounce sinker and a small split shoot simply to keep the bigger sinker away from the hook. I fish the bottom during the daytime hours and I bobber fish for them at night, setting my bobber about 2 and 1/2 to 3 feet deep and casting towards the face of the dam.
Happy cat huntin'!