Somewhere in the mysterious land of sonar menus, hidden windows and secret subroutines lies a little known fish-finding function. Think of it as a super interesting on-screen app that can instantly help you locate and catch more fish. Rather than a rendered interpretation of fish and structure, live underwater video provides the final word on what lies beneath. As anglers continue to discover, their Lowrance, Garmin and Raymarine sonar-chartplotters offer the powerful ability to connect an Aqua-Vu camera and view…