I don't know much about BC, but flatheads will eventually eat every fish in your pond of 1/2 acre. Yep, you will have some big flatheads but nothing else and the flatheads will only grow until they run out of food. It happened to a guy up the road who had a pond with too many little bluegill. He only pu 2 flatheads, one 10 pound and one 8 pounds out of our local river in to control the BG. When he drained the pond 7 or 8 years later to clean it out, the 2 catfish were the only fish in it. One was about 25 lb and the other about 18. A few would be okay in a much larger pond or lake.