Portable Fish Finder, and Hummingbird Fish Finders. A marine discount is good. Click on the items to the left and see what discounts we have. You can find everything from the big-screen, 640 x 480-pixel, liquid-crystal monitors that show many colors to the black and white models, and even see the difference in portable vs. non-portable ones. Of course, you still need to be good at fishing and know the correct movements to make like the movement that continues until a considerable amount of line is airborne. You need to know why certain things enable the angler to cast the fly onto the water without disturbing the surface. And just for fun, you may like to know information about your prey, like the fact that gills are made of a series of thin sheets or filaments through which blood circulates.