Flatheads hang out at restaurants on Lake Houston and they will aggressively eat anything you drop off the deck. They definitely eat tortilla chips.

I would consider getting the cheapest dog food you find at WallyWorld and try that. If your feed store has cheap goat chow etc I bet that would work too. There has to be a commercial catfish chow for commercial growers.

Of coarse, when Fritos go on sale...

4 acre pond 32 ft deep within East Texas (Livingston) timber ranch. Filled (to the top of an almost finished dam) by Hurricane Harvey 9/17. Stocked with FHM, CNBG, RES 10/17. Added 35lbs RSC 3/18. 400 N LMB fingerlings 6/18