I know that poppers will be good flies to use once the water warms up for bass and bream, but what would be a good fly for them now in the colder part of the year?

Also, I fish one pond that is full of chain pickerel, and I intend to try and catch some of them on a fly. When I fish for them using a bait that they can get into their mouth easily (this is when I'm using a spinning or baitcasting reel, not while flyfishing), I either use a leader that is at least 20lb mono or a light wire leader. I'm wondering what should I use as far as a tippet goes. I would also like to know what a good fly to catch them would be. They mainly feed on wild shiners, bluegill, and probably other pickerel and bass. I talked to a guy that had just been flyfishing in the other end of the pond and he had caught some on some sort of streamer he tied himself, and that was all he said about it. He also said the only reason he left was that he didn't bring enough tippet because he was getting bitten off so much. He was using 15lb fluorocarbon. If you have any experience in the flyfishing for pickerel or have any advice to give, I would appreciate it.