How To Read A Fish Finder Screen (A Beginners Guide to Fishfinders)

For beginners in kayak fishing, one of the most frequently asked questions is, “How do I read a Fish Finder Screen?" If this is you, we have got your back on this.

In this article, we are going to show you how to read a fishfinder screen to help you become a better angler. 

While fishfinders are great for letting you see what’s underneath your boat, they also allow you to have a clear view of how fish responds to your bait and help you spot where fish congregate.

Most fishfinders use sonar technology to shoot a beam straight down to create an image in the water. In return, they give you a SMALL amount of bottom coverage. Even though the Sonar coverage isn't going to give you the most result, you can still read the screen sonar effectively just by applying a few tricks.

Identifying Fish

The first thing you need to learn is how to identify fish. For fishfinders with Fish-ID technology, identifying fish can be a breeze. This technology converts the raw data gotten from the water into a user-friendly interface to help you interpret what is below you.

Fish Icons


The Fish-ID technology type of fishfinder will help you locate tiny fish icons. You will get to see them in different sizes and lengths. The best part is that you can also view different icons for plants, rocks, and schools of fish. 

What is required of you is just to read the Icon displayed on your screen and understand the depth of the displayed icon?

However, you need to be a little bit cautious with this; most Fish-IDs do come with their own downsides. Most times, what your Fish ID will display as a school of fish might turn out to be a group of plants after you have cast in your net. But with frequent practice, you will get the hang of how to use them effectively.

Fish Arches

If you have an arch fishfinder, then expect to be receiving lines and arches from the transducer. This type of fishfinder will save you a lot of time once you understand how they work.

They represent fish as arches more clearly than Fish IDs. So when your fishfinder shows bigger arches, it means it has detected a big fish, while small arch will translate to smaller fish.


Though it might be a hassle trying to identify rocks and plants from arches, with time, you’ll get the hang of how to use and understanding your fishfinder images to identify structures and classify fish based on their location and size.

Judging Fish Size

As earlier said, a bigger arch means a bigger fish. But there's more to this as this may not be the case in every situation. We are going to analyze this based on the thickness, length, and fullness of the arches.

In the image the black vertical lines show how long the fish is under the transducer and the green lines show the thickness of the fish arch.


Fish Arch Width

So, if the fishfinder doesn't show you the actual length of a fish, can it then show you the arch width?

Yes, you’re likely to get the actual size of the fish is you look at the width of the fish arch.

Here's the idea:

Always look at the thickness of the arch instead of the size. If the fishfinder gives a return of a full arc, then it is likely to be a big fish. So if you get a return of school of fish of the same size, you can easily spot out the biggest one with the thickest size. 


On this screenshot is a 7.5 lb. northern pike, you can see when Doctorsonars set the hook and started bringing him to the surface.


Via: Doctorsonar.com

Half Or Full Fish Arches


The arches on your fishfinder can either be full or half arches. Your fishfinder screen will display a full arch if the fish swims to the entire sonar cone. But it will show a half arch if the fish only swims through part of the sonar cone.

The most important thing to keep in mind is that a half arch doesn't necessarily mean a small fish. There are still high chances it could be a big fish.


So, the size of the arch doesn't indicate whether it is a big or small fish. What we recommend you keep an eye for is the thickness of the arch as this is the best way to know whether it is a big fish or not. 

Finding Baitfish on Your Fish Finder

Baitfish will display on your fishfinder as dots, dashes or even lines. A group of baitfish could often be seen in balls and are always suspended in the water.

You will also see them in a yellow color, than in green color of vegetation.

Spotting A Trophy Fish On Your Fish Finder Display

The best way to locate a trophy fish is to look at the previous tip we dropped earlier. The best indication to know that you've seen a bigger fish is to always look at the width/thickness of the fish arch. It doesn't really matter if the arch is full or half--the main indication you should be looking at is the thickness of the Arch.


Identifying Different Types of Underwater Structure

By understanding sonar and interpreting the display, you can read the depth, determine the bottom contour of underwater structure to help you mark fish. And a cool feature that can give you a broad view into this is the depth finder feature.


The depth finder on a transducer lets you know the depth of the water underneath your boat. It also tells you the type of fish to expect in that river. Usually, the depth finder feature can easily be seen in most fishfinders on the top left corner of the screen. It works, using meters instead of feet as its scale of measurement.

Aside from this, the depth finder feature does a fair Job in showing you water temperature to help you know the type of fish you're going to catch.

So, always make sure you're trolling or scrolling your fishfinder at a slow speed in order to get an accurate view of the bottom contour. With this, you will be able to identify a drop-off. And if you do, ensure you scan that area again by switching from the wide beam scan to a narrow beam scanning. 

This will give you a more accurate picture of the contour change, and also help you avoid any ‘dead zones’ while scanning.


Also, if you're reading a deeper sonar, a bathymetric mapping system will come in handy in helping you create color-coded underwater contour maps. Aside from this, these maps will also display depth changes, and drop-offs and show you the best spots underneath your boat.

Another tip to keep in mind when fishing in a larger area is to set a depth alarm to let you know when you reach a given depth range. This will allow you to paddle over shallow waters with less hassle and help you identify a range of species like predators.

Vegetation And Weeds

There are times you will want to choose areas with vegetation and plants as your potential areas to cast. Just like looking for logs, your fishfinder will display a spotter return or vertical lines on your fishfinder screen when you bump in areas with vegetations.


If you want to spot depressions when you are carp fishing, make sure you watch out for tiny, v-shape dips in the bottom contour as you stroll or reel.



You can easily spot points since they are more gradual than drop-offs. To get an accurate reading of how steep the incline is, ensure you’re reeling or strolling at a steady speed.

Also, make sure you scan with a narrow sonar beam to have a clear reading of humps and shelfs, which a wider beam might fail to pick Up.

And Judging bottom Types and Hardness

How do you read a 2D sonar fishfinder to determine the type and hardness of the bottom underneath you? Here a few things to keep in mind.



As earlier said, once your fishfinder returns, a stronger echo, it then displays a thicker, bold line. Meaning, the bottom of the water it encounters is less porous and a lot harder.

But what about if the transducer displays a thin, light line? Then it is showing you a softer water bottom like clay. 

Colour and“2nd Returns”


Another thing you need to understand about fishfinders is they do come in either color or Grayscale( black&white).

Models with colored fishfinder will display high and dark color if the echoes returned by the transducer are powerful. In other words, if the transducer returns a stronger echo, then fishfinder will display a stronger or darker color.


Darkest color fishfinder


Colored fishfinder

The darkest color your fishfinder will encounter will be the returns it gets from details like seabed or the bottom of the water.


How To Read A Lowrance Fish Finder Screen?

Reading your Lowrance fishfinder screen is very easy and straightforward. Once you set it up and running, the next thing you will see is a display of metric and numerical value in the upper left corner.

This will let you know the water depth underneath your boat. Also, ensure to set the automatic mode active to give a precise value of both boat speed and temperature.

Check out this guide about "How To Read A Lowrance Fish Finder" for a more in-depth guide.

How To Read A Garmin Fish Finder Screen?

The Garmin fish finder is a unique unit that utilizes sonar and sound navigation techniques to catch fish in the water by receiving reflected pulses gotten from sound energy. So, with this device, you will be able to read the info from the reflected sound to find a school of fish underneath the water easily.

We have prepared a video to guide you to know how to use the Garmin fish finder efficiently.

How To Read A Humminbird Fish Finder?

Reading a Humminbird Sonar fish finder is pretty easy. It offers a user-friendly interface coupled with the utmost simplicity in mind. Featuring a digital display screen, you can read information either through the graphical or numerical display.

All this provides you with the water depth, a clear picture of bottom contour and even fluctuations in water temperature. As a non-tech savvy, you are going to learn all you need to know to use your hummingbird-like a pro.

Here is an excellent video for this

How to Read A Simrad Fish Finder?

The Simrad is the best fishfinders with an intuitive design. It offers a faster and responsive touchscreen, compared to that of Lowrance or Garmin.

To back up this hype, this unit comes with a high-end features, extensive networking, like radar support, ForwardScan, TripIntel, and a host of other cool features to make your fishing experience a breeze. Here is a short video of how to read a less expensive fish finder like Simrad.

How to Read a Side Imaging and Down Imaging Fishfinder Screen?

Down imaging is probably different from the traditional sonar we are mostly used to. While fish may look the same with a 2D sonar, fish do appear smaller on side imaging because it features a down beam that comes as a narrow slice of the water column.


So you’re likely to see something like Crappie looking like circles, or small ovals. Spotted bass will stack each other while schools of bass will disperse on the bottom. 


That said, you will be able to view hard bottom on Down Imaging as a little brighter soft bottom, with a thicker band of color under it.

Side Imaging Sonar, on the other hand, offers beams on the side to give you brighter returns on fish. It also displays sonar shadows to let you know if a fish is off the bottom of the water. So knowing the distance with the shadow and the fish will let you know how suspended the fish are. 

Our Vedict

Fish finders are lovely machines that allow you to quickly discover fish to make your fishing experience a total joy. I hope this article was helpful and gave you an insight on how to read a fishfinder.

If you have any question about this, you can leave a comment down below.