page title icon How to Read a Fish Finder Display Correctly [ Complete Guide ]

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Spending less time and catching more fish while exploring nature’s beauty is a dream of every angler. Thanks to the combination of state-of-the-art fishing boats and advanced fish finders for making things easy for the anglers. However, as simple as most of the best fish finders look like, getting the most out of them is one of the important objectives of all the anglers. Based on the same context, we’ve compiled all the information at one place that’ll be more than enough for you to get the most out of your fish finder. At the end of this article, you’ll know ‘how to read a fish finder’ in no time.

If you already know “how to install a fish finder“, then what are you waiting for? Grab your best fish finder, board on your fishing boat, and let us help you catch your very first fish. You’ll find most of the useful strategies in this article that professional anglers personally use. You can make your trip memorable, exciting, and fun while catching more fish in less time and get the most out of your weekend getaway.

fish finders devices

4 Important tips for reading a fish finder correctly

The fish finder is an automated digital device that makes fishing a breeze, enjoyable, and fun. The photographic and high-definition images featured by a fish locator let you see what passes below your boat in real-time. You can see structure, submerged objects, fishing baits, and targeted fish with great separation.

The below steps will help you how to read a fish finder accurately in no time.

1- Understanding and getting used to the Display

One of the primary purposes of the user-interface of a product is to engage customers through visual interaction. The accuracy and output of your fishing will depend upon two factors primarily. Firstly, how well you understand your unit’s display and secondly, how easily you can distinguish different targets from each other.

Reading the manual

Fishing from a boat equipped with fish locators grants you countless opportunities to fish more in-depth and less-crowded waters. But there are two most important things to know before you set foot on your first fishing trip. The first is to understand how the depth finders for boats work. Secondly, how they reflect fishing details on the display screen and how you can read the fish finder’s display properly .

The manual is very convenient to understand the essential information because it clearly explains all functionalities with images and visuals.

Reading your device’s manual will solve almost all of your queries as it’ll have all the answers to your questions. If any problem arises or you get stuck in the middle, following the manual is your easy way out.

Understanding the necessary information

Most of the fish finders provide all the fishing information in real-time to effectively increase your fishing productivity.

Having essential information at your fingertips, including the boat’s speed, water depth, and distance from shore, can let you do more fishing in less time. 

The depth finder display has all this essential information typically grouped, either in the top left or top right corner. This information’s exact location will vary depending on the brand and model of the fish finder you’re using.

fishing insights

Reading the display of a Downscan Fish Finder 

A Down Imaging Fish Finder reflects the most recent underwater data towards the right of the display screen. The oldest data is gradually shifted by the display toward the left.

Even if your boat is stationary and motionless, the unit will still reveal all the details. The moving display shows the fresh data on the right of your fish locator and pushes old data on left side.

Reading the display of a Sidescan Fish Finder

In a Side Imaging Fish Finder, the object that displays on the top-most screen is your fishing boat. Moreover, all the details below are what your boat has passed over.

The details shown at the top of the display are the most recent and newest data. In addition to this, the data moving slowly to the bottom is older data that your boat has already passed.

2- Locating Fish and Mapping the Area

Once you understand all the necessary information of fish locators, the next doable action is cruising to your favorite spots. Moreover, you can map the whole area in no time and quickly locate your favorite fish with Sonar technology.

Look for small spots or arches if you’re trailing smaller fish

The blobs or small patches detected in Sonar mode are probably perch, pole, or other commonly found small fish. In a Side Imaging fish finder, the small fish or bait fish look as little dots or arches on display.


Look for arches or large dots if you’re after bigger fish

Trout, catfish, and other fish of similar size appear as large arched shapes when you’re using the traditional Sonar Mode.

In the Side Imaging mode of Sonar fish finders, bigger fish will appear as large dots on the display screen. More the yellowish color the arches have in them, the more bigger target fish you’ll be seeing on your unit.

big fish

How to understand the type of water terrain

The solid thick line near the bottom of your display indicates the water base where you’re fishing. The reddish yellow line is the default color in fish finders mostly that marks the surface beneath the water.

If your display is showing more details below the bottom line, it means you’re moving above a soft bottom. A water with soft bottom means, you’re most likely floating above sandy or muddy water. Moreover, if you can’t see more details below this thick line, then you’re either above a hard or rocky surface.

Understanding the different types of fishing terrains on gives you important insights related to fishing. It enables you to look exactly where you should, when hunting for fish in rocky areas or soft underwater bottoms.

Water Bottom

How fish finder Chartplotter combo can increase productivity

If your fishing unit features a Chartplotter as well, then you can switch it over into split-screen mode. That way you’ll be able to use it as a combination of with the fish finder.

Using the combo comes in handy when you notice schools of fish on the display due to unusual underwater activity. You can mark those specific spots on the Chartplotter so that you can find those spots in the future easily.

If you use a model that doesn’t have an integrated Chartplotter, there’s nothing to worry about. You can achieve the same goal by marking potential waypoints on a separate Chartplotter.

3- Adjusting the display to get improved results

Adjusting the display of boat depth finder according to different fishing environments effectively increases the productivity of fishing trips.

The necessary adjustments immediately help you capture more underwater details in less time spent. Additionally, a more readable display let you know more underwater details. As a result, it enables you to catch more target fish in less time. In the end, you end up with a memorable fishing trip and an unforgettable experience.

Get desired results by focusing on areas of interest

Zooming in on the areas of interest helps get clearer, detailed images about your target’s activity at a particular depth. If you have done proper research about your target fish, then this feature is handy and useful for your fishing.

You simply instruct the fish locator from the option menu to zoom in on a specific depth range in water. As a result, your display will solely focus on that area of water specifically; this will introduce more accuracy and output in your fishing.

Adjusting the color palette to make the display brighter

The default display lettering of most of the fish finders is white with a black background. Changing the default display settings to show black letters on a white background makes the display brighter and more readable. Moreover, you can easily interpret and distinguish target fish from underwater details of the terrain.

Adjust the update speed to constantly get most recent data

The update speed is a feature that defines how fast you’ll receive data on your display. If your unit’s update speed is low, you’ll mostly get outdated and old data with no potential value. Likewise, if the update speed is slightly high, you’ll get the most recent data first. Without any doubt, the up-to-date and fresh data possess more potential and underwater details.

Using the fish ID feature to Catch More Fish every time

The fish ID is an innovative yet useful addition to the latest and best fish finders. It interprets the lines, dots, arches, and visual data and shows you where the fish and other underwater targets are.

The fish id feature is very beneficial for new anglers because of a lot of reasons. It enables you to jump over the fishing curve required to interpret the visual details of a Sonar fish finder.

fish id

4- Peaking the transducer to get more details from a fish finder

Peaking the transducer is a process where you manually adjust the device’s sensitivity. Peaking is the ultimate key to get the most up-to-date and accurate underwater details from any depth finder.

There are pros and cons of how much power output your fish finder will possess during fishing. Too much power output will saturate the display screen with clutter and unnecessary details. Too little power output will not display significant underwater details such as thermoclines, baitfish schools, and even your target fish.

Adjusting the automatic settings manually

Sometimes the fish finder gives incorrect and false information with the default automatic sensitivity settings. The inaccurate information fails to help you find fish in the area where the fish locators suggests fish are active.

Manually adjusting and fixing the sensitivity settings will help you get rid of these inaccuracies and errors.

Fix the range to at least three times the depth of fishing water

Setting the range at least three times the depth of the water you’re fishing gets you more accurate underwater results.

For-example, If you are fishing in depth of 20ft, you need to manually adjust the range up-to thrice the depth. In the light of this consideration, 60ft is the range that’ll get you better results.

Raise your unit’s sensitivity till you see two readings on display

The correct technique to increase your fish finder’s sensitivity depends on the specific model and brand you’re using. You can manually modify the sensitivity using the settings menu or by pressing setting buttons present on the fish finder.

When you’re increasing the sensitivity, you’ll have to gradually increase the sensitivity of the unit. A stage will come when you’ll see a second reading on display with prominent clutter and messy details.

Decrease your unit’s sensitivity until all the messy clutter is gone

You can reduce the saturated clutter on the screen by slowly dialing back and gradually decreasing your unit’s sensitivity. When the second reading becomes clear, you’ll get a better idea of what’s below your boat with clear underwater images.

Avoid adding filters to reduce the fishing surface clutter

Most of the fish swim quite a way from the range of the water surface and your boat. You should avoid increasing the filter strength or use filters to reduce surface clutter. It is unlikely to help you find fish as adding filters or increasing filter strength will affect the sensitivity.


Liam Maxwell is a professional with two years of experience in fishing. He has been working as a fisherman for the past five years and has worked on many different vessels at sea and dockside. His expertise is primarily in commercial fishing for tuna, swordfish, marlin, shark, and other aquatic species. Joseph also possesses considerable knowledge about fish handling techniques such as fish finder, cutting-in (seizing), gilling, or gutting.