How to Read a Fish Finder Screen

Gone are the days when fishing was just a simple procedure. Fishermen used a simple fishing rod, a primitive reel and some bait and could successfully take a bucket full of fish home. However, time changes everything. 

read fish finder screen

Unfortunately, today fish populations are threatened by climate change, pollution and overfishing. Consequently, you cannot find them easily and they became really suspicious. 

Fishing is a philosophy that continues to develop throughout the history so you will need the help of modern fishing technologies. The fish finder also called depth finder is a smart and useful tool especially for saltwater anglers.

How much does a fish finder help? 

Undoubtedly, this smart device is a must have part of your saltwater fishing arsenal and you should have the best fish finder mounted on your boat. Firstly, a fish finder informs us about the water temperature, depth, bottom structure or underwater obstacles. Moreover, a gps fish finder has built in maps. A fish finder screen is the hallmark of navigation. 

Since it is a significant tool, we decided to put a short guide together and show you how to read a fish finder screen.

How does a depth finder work?

First of all, many of you may be not familiar with those "new" tools, so it would be a good idea to learn some basic fuction features. This device uses sound waves (signals) to locate objects and determine the depth and bottom structure. In addition, there are two basic sonar types, passive and active.

Passive sonars are used only for military purposes to detect submarines or enemy ships. These sonars only receive signals ans do not emit. Obviously we are going to talk about active sonars which emit and receive signals. 

The typical sonar utilizes a central main unit and a sensor also known as transducer or eye. The main unit is the fish finder screen. We would like to underline the fact that you should take care of the sensor. 

A dirty or damaged transducer could five you false results. 

The transducer receives electricity from the main unit amd converts it to mechanical energy and vice versa. When the pulse is transmitted through the water, the water molecules vibrate and produce signals.


Furthermore, the signals travel through the water and "hit" on objects or fish so the signal returns to the transducer. Reading fish finder screens is not difficult but you should definitely know how it works.

If you want to find the best fish finder, you should choose wisely. Many manufacturers hype their products. So before you get a product you will have to search the market thoroughly 

How to read a fish finder screen

Before we start analyzing some basic things you should determine if you need an expensive or cheap fish finder. For instance if you want a kayak fish finder you definitely not need an expensive device.

If you are an inshore fishing fan, the best solution for you would be a wireless fish finder! You just throw the sensor in the water and it transmits information through wifi to your smartphone. 


  • Transducer and Frequency 

To begin with, the transducer should be installed by an expert. Certainly, there are many mount options available but accuracy is essential here. Our transducer is the "Underwater Eye" of our boat. 

The sensor should be able to convert any form of energy with the least possible loss so they can give you an accurate result on the screen. The eye is made of some piezoelectric elements and the thickness and type of this material determines the operating frequency. The lower the thickness, the greater is the frequency. 

What Frequency Should I use? 

When you read a fish finder screen the first thing you see is the frequency. Water definitely affects the signals. You should choose the appropriate frequency according to the depth of water you are going to fish in. 

Water can absorb more signals when they are higher. Consequently, high frequencies will give you an accurate resolution on the screen and more details. On the other hand, low frequency signals can travel longer distances, but there is a significant detail loss. 

Thus, for deep waters you will use low frequency. 50kHz is ideal. There are ample products on the market but top rated items have better features. 

A hummingbird depth finder or garmin depth finder are top options. They are fully equipped with cutting edge features. 

  • Top Down Imaging Sonars

    Undoubtedly, each device has some unique features and that depends on the brand and product. When the main unit receives signals, you will notice lots of arcs on the display. These arcs are actually fish and other objects! 

    Top down view is not the best but it is quite good for kayak fishing enthusiasts. Overall, these kind of sonars are not preferred. 

    • Side Imaging Sonars
    View of fish finder

    It goes without saying that a side imaging sonar will bring you to the next fishing level. The transducer is pointed out to the sides of the vessel and covers a big imaging area. On the display you will see two sections divided by a line. 

    Side imaging fish finders are the best options for saltwater anglers because they will show more details. 


    Finally, it is obvious that you will not use the same fish finder for both tuna fishing and salmon fishing. The fishing technique, the water depth and structure are definitely some factors that you should take into consideration. 

    The depth finder options are numerous but you should find one that will fit your needs. Thank you for reading and stay tuned on!

    Pic of Coastal Fishing Drawing




    Fishfinder View
    Cheap fish finderDepth finderDown imagingFish finderFrequencySignalsSound wacesTransducerWireless fish finder

    1 comment

    john Bass

    john Bass

    Stavros, it was a very enlightening article. thank you

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