How to Read A Fish Finder (Including Garmin)

Beginners in kayak and boat fishing seek to understand how to read a fish finder, an essential tool for a fruitful fishing experience. Fish finders come in various designs, sizes, and configurations; therefore can be intimidating for complete beginners.

They all operate in a similar style, and their results are relatively the same. Reading a fish finder does not vary as much from one model to the other, as long as you install and set it up correctly.

If you are figuring out how to read a fish finder and looking for a comprehensive guide on the same, this article is a great resource. It will take you through the steps of interpreting the display to guide you on how a fish finder works.

Reading a Fish Finder

How To Interpret The Display

Fish finders come fitted with displays that give you an overview of the underwater environment. The display features vary from one model to the other, even though they work similarly to translate the conditions under your boat and how fish respond to bait.

Most fish finders on the market use sonar technology, which involves shooting a beam straight down to create a picture of the underwater environment [1]. This feature then translates the findings to an image that displays on the fish finder’s screen.

How To Identify Fish

The main aim of using a fish finder is to identify fish schools and their movement for more precise targeting. Depending on the model of the fish finders, specific icons will display on the screen showing you how fish are distributed underwater.

Identifying Fish Icons

Fish finders with Fish-ID help you locate tiny fish icons that display on the screen. These fish icons display in different sizes and lengths according to what is under your boat. The best thing is that such finders show icons of plants and rocks, giving you a clear underwater view.

When reading the fish icons, you need to understand the depth of the displayed icon to determine how deep you need to cast. However, you should not use the displayed depth to accurately represent how deep to cast your net, as most finders give a rough estimate.

Identifying Fish Arches

Arch fishfinders display fish in arches of different sizes to show the various sizes of fish underwater. These fish finders are easier to read than Fish-ID ones as bigger arches indicate bigger fish while smaller arches indicate smaller fish.

The only downside to this is that the arches can be challenging to sift through images of plants and rocks. But, with time, you get the hang of it and understand how fish images translate on the screen.

There is more to reading the fish arches as shown on the screen. The thickness, length, and fullness of the arches all read differently. The width of the arch directly translates to the width of the fish.

The same goes for the length and the fullness. The fuller the arch, the bigger the fish. If you get arches of the same size, crumped up together in one place, that indicates a school of fish, relatively similar in size.

Another point to note is distinguishing between a full arch and a half arch. A full arch shows the fish swimming to the entire sonar cone, while the half arch indicates a fish that swims through part of the sonar cone.

Half arches do not translate to small fish; there is a high chance they are as big as full arches on display. Keep an eye on the thickness of the arch to differentiate between small fish and big fish.

Reading Baitfish on Your Fish Finder

Bait will appear as dots, lines, or dashes in most fish finders. If many baits are grouped, they will appear as balls suspended in the water. They appear in yellow, while the vegetation around them appears in green.

Reading the Underwater Structure

Once you understand how sonar technology works and how to interpret the display, you can read the depth and determine the bottom contour of the underwater environment. This information is crucial to help you mark fish for the best fishing spots.

Reading Depth

Transducers come with depth finders that estimate the depth of water from the bottom of your boat to the floor of the water body. It also has a unique feature that reads the type of fish under the water.

Most depth finders show on the top left corner of the display and mark it in meters instead of feet. Additionally, the depth finder shows you the temperature of the water, which is crucial to determining the types of fish to expect.

The best way to get an almost accurate depth reading is trolling your fishfinder at a slow speed. That way, it has enough time to scan the bottom contour and calculate the distance. While at it, switch between narrow beam scanning and wide beam scanning for more accurate depth readings.

Identifying Vegetation

Areas populated with vegetation can be potential spots for a high yield, but you need to understand how these read differently from fish on your fish finder. Vegetation reads as vertical lines, which in highly-populated areas, the lines are crumped up together.

Spotting Depressions and Points

Fish are likely to hide in depressions under the water. These read as small v-shaped dips in the bottom contour showing the difference between the flat floor and depressions.

Points are more gradual than depressions and are not as sharp as depressions read on the screen. You can get an accurate reading of the incline by reeling slowly and using a narrow sonar beam. This method gives a clear view of humps and shelves, differentiating them from depressions.

Understanding Color

When it comes to color, fish finders come in either color or greyscale- black and white. Colored models display dark color if the echoes the transducer returns are powerful. In simpler terms, if the transducer translates a stronger echo, the color will be darker.

Also Read: Fish Finder vs Depth Finder

How to Read a Garmin Fish Finder

Garmin fishfinders are some of the most common on the market, hence the need to learn how to read them. Garmin fish finders utilize sonar techniques and sound navigation to detect fish and read the underwater structure.

Here are steps to read a Garmin Fish Finder [2].

Step 1: Power the Device On

Press the power button to turn your fish finder on. Most Garmin models have a red circular power button, so it should be easy to find.

Step 2: Read Water Depth and Temperature

Check the screen’s top-left corner for the water depth reading. Usually, the measurements are in feet, unlike other models that indicate the depth in meters. Next to the water depth reading is where the temperature reading displays, usually in Fahrenheit.

Step 3: Read the Bottom Contour

The lines at the bottom of the fish finder screen indicate the water surface bed. If you read an upward slope from one side to the other, your boat is moving toward shallow water and vice versa.

The thickness of the line on the screen indicates how coarse the underwater surface is. That said, the thicker the line, the rougher the surface.

Understand the Underwater Geography

The lines extending beyond the surface-indicating line are essential as they describe the geography of the underwater environment. These will help you figure out moving and non-moving objects, including natural and unnatural structures.

Dark-colored humps on the screen indicate rocks. Sound waves reflecting long lines show underwater vegetation while lines show trees. These can guide you on how everything under the water is distributed for a better fish-finding experience.

Understand Displayed Images

The screen that shows surface-indicating lines is vital to pay attention to with a Garmin fish finder. It shows the water between the water surface and the surface below the water.

Hook signs show the different types of fish, with large hooks showing large fish. The area with most of these hooks is a hot spot for fish where you should focus on. Pay attention to how far below or how close the surface is to get the exact position of fish schools.

Related Post: How Does a Fish Finder Work?

The Bottom Line

Fish finders are easy to read, as long as you understand what every icon on the screen means. This is a general guide on reading fish finders that applies to popular models. With the correct settings and proper installation, you can identify hot fishing spots with your fish finder.


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