Trouble Marking Fish

My unit is not properly depicting fish. What should I check?

Shows Few or No Fish

If you are not seeing many or any fish on your screen but you are catching fish, you need to consider the following:

  • Transducer Location - with traditional 2D sonar, the sonar beam is shooting down from the transducer. Therefore you are only seeing what is directly below the transducer and this information is history, as it scrolls across the screen from right to left.
  • Fishing Location vs Transducer location - if your transducer is located on your transom and you are fishing off your bow, and casting 15-20 feet (or further) from the bow, you are fishing no where near the sonar beam.
  • Depth of water - traditional 2D sonar only shows a width of 1/3 of the depth of water you are in. So if you are in 10 feet of water, you are only seeing around 3 feet at the bottom and even less as you come closer to the water line.
  • Cone Angle of transducer - your area of coverage of the bottom is directly related to the cone angle of your transducer. The wider the cone angle, the larger the area of coverage is. Here is an example of area of coverage where you can enter your water depth and see what your bottom coverage is at various cone angles. Check your products specifications to determine it's cone angle.

Fish Symbols vs. Pixels

Not all models of depth sounder will show a fish symbol for targets that are detected. Some will only show them with a pixel or a group of pixels. Some models of fish finders have the option to show detected targets as fish symbols or the raw sonar data. Consult your Operations Manual for your depth sounder capabilities.

Check for Simulator Mode

Check that your depth sounder is not in simulator. With the depth sounder turned off, momentarily press the power button. Some models will flash or scroll the word "Simulator" on the display.

Features and Menus

For those depth sounder with the following features and menus, try adjusting them as stated:

  • Sensitivity - adjust all Sensitivity menus to a higher setting.
  • Gain - increase this setting.
  • Fish ID Adjust - increase this setting.
  • (Noise) Filter - turn the filter OFF.
  • Beam - turn all transducer beams on.
  • Water Type - set to present water type.
  • Surface Clutter - adjust so that less surface clutter is blocked.
  • Turn off any other depth sounders
  • Bottom View - adjust to Inverse (Grayscale) so that weaker signals will be easier to see on the display.

Check the Transducer

Check the Operations Manual and Transducer cable for the proper transducer for your model. Normally, the transducer name is marked on the cable within the first 6 inches from the connector end. The correct transducers to be used with your unit are listed in your Operations Manual.

Check for proper transducer installation according to the Operations Manual. If the transducer was installed to "shoot through" the boat hull, the installation may have degraded allowing air bubbles to be trapped between the transducer and boat hull. It may be possible to check for this by adding enough water to the boat hull to partially cover the transducer. The water may displace the trapped air and allow the transducer to work properly. If this happens, the only long-term solution is to try and remount another transducer in your boat's hull.

Check for Marine growth or other obstructions that may be on the bottom of the transducer. Some Anti-fouling paints may not be used or may only be used in a single thin coating. Clean the bottom of the transducer with soap or detergent and water or lightly sand with sanding paper. This will help "wet" the transducer. When putting a transducer in the water, it may form air bubbles across the face or "eye". This can be simply rubbed away with your hand. Older model transducers have to be allowed to wet before they will work properly.

Fish Variables

The size of a fish's air bladder helps determine the size fish displayed. There are many variables that affect this, some of which are:

  • The species of the fish. You may be over a large fish such as a flounder, however because it has a small air bladder and according to your fish finders settings, it may be displayed as a small fish or not at all.
  • Whether the fish passed directly under the transducer or off to a side. If a large fish were to pass to one side of the transducer, its air bladder may not be fully in the transducer cone angle. This will cause a much weaker return signal to be reflected back to the depth sounder. A weak return signal could be displayed as a small fish or as baitfish or due to various settings on the depth sounder, not at all. If the same fish were to pass directly under the transducer, it could be displayed as a large fish.

If you are still having problems after trying the preceding suggestions, please contact our Help Center.

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