My best friends family back home (on the Missouri River) didn't have a ton of money and lived on butchered cows, canning their garden, and wild game. They used to bank line for flat heads, bring them home in the afternoon, and put them in a cattle watering tank with an aerator and filter. They would feed them dog food for a week and "clean them out". I don't know if it did or not, but it was darn good eating.