Residents from 13 states and Canada are in Warren County this weekend to compete in the inaugural Musky Fly Fishing World Championship.Participants can fish in any Warren County river during the one-day tournament this Saturday.“This is a great place for musky fishing,” said Illinois resident Chris Willen, who got in a practice round Wednesday on the Collins River. “The musky is the hardest fresh water fish to catch. It’s known as the fish of 10,000 casts.