Before cooking any species of catfish, whether it be Blue Cat, Channel Cat, Flathead, or Mud Cat, I would soak it overnight in a salt water and vinegar solution. This would remove the strong flavor associated with fresh water bottom feeders.
Carp, I never considered edible. We would catch them by the sack full for garden fertilizer. Although my Dad used to tell stories about how he and his brothers would catch them from the city park ponds and take them to the part of the city they called "Jew Town" and sell them. Evidently Kosher dietary laws prohibit eating fish with no scales like Catfish or Eels, but because Carp had big scales, they were in demand.