The sensitivity or gain on your finder is probably the most important feature on it. The higher that this is set the better picture you will get on your finders screen. Too much though will result in "clutter" showing on the screen. The finder needs to be run in manual so the fields can be custom "tuned" so it will show what is really down there. If set up right a good finder with adequate power should be able to show small fish. Not all fish will make a nice fish "arch" as most expect. A small block or blob can be a part of a fish. This depends on where the fish is in the transducer's cone or it's direction of travel. The thermocline usually appears as a faint line on the screen. I have even seen a double thermocline in some instances. Once it is picked up it will fade in and out and not always be a consistant line. The line will wander up and down in the water column also. I belive some finders are designed to show the thermal breaks more defined than other units. I use a Garmin 240 monochrone and have had really good results with it. On some of those slow action days adjust your finder by scrolling through the menus and see what is available to be setup on your finders. Good fishing!
