GARMIN Fishfinder 90 GPS Marine. The Fishfinder 90 wraps simple operations and Garmins exclusive fishfinder technology into an entry level sonar. It is perfect for any vessel where space is at a premium. Dual beam transducer operation gives you better shallow water performance. The wide viewing angle 60 degrees lets you see fish even off the sides of the boat. With a basic black on white display, the Fishfinder 90 has one of the sharpest screens for the money. The Fishfinder 90 also offers Ultrascroll which allows boaters to get a much faster refresh rate on their sonar display. AutoGain, as well as user adjustable gain, is also standard on all of Garmins new fishfinders.