Recently I've started targeting bigger fish, I've been bottom fishing a lake near by with bluegill as bait. It has treated me with several nice sized channal catfish (5-8lbers) . Today I hook the biggest fish of my life, I'm assuming a flathead atleast 20lb. I was running 30lb mono with a slip sinker to a swivel with 25lb mono leader. The fish picked up the bait and I let him swim a few feet with it before setting the hook. He headed straight for deep water, my drag was far too tight but he managed to pull several feet before breaking me off at the hook. I was using an improved clinch knot. Could that (plus my drag) be have been the problem? What knots should I use for heavy line and big hooks?