How Does a Fish finder Work? [The Complete Guide]

Fishing is a sport, a pastime, or whatever you want to describe it; it is unique to each person, but it is an activity that is full of fun and delight. However, if you are in muddy waters, this activity will become complex and stressful. Even the most transparent waters can become murky and difficult to see through, affecting your fishing trip.

When fishing in deep waters, you look through the water with your unaided eye to see what kind of fish you might make in that body of water. You will not see anything if the water is not clear enough, leading to an unsuccessful fishing expedition. However, there is a way to ensure that your fishing trip does not go astray, and that is through the use of a device known as a fish finder.

A fish finder is a gadget used by various people, but mainly fishermen, to locate possible catches in water bodies. This gadget uses the SONAR technique (sound navigation and ranging). This equipment is still valuable today for people who catch fish professionally or for leisure.

A fish finder can be fitted with GPS, marine radar, and a compass, depending on the brand you pick, to assist you in navigating when you are on a boat or kayak. Fish finders use sound to detect objects underwater. They operate by emitting sound pulses and listening for an echo. The frequencies employed range from extremely low to extremely high.

Workings of a fish finder

A fish finder uses a screen, either LCD or CRT, to show a fish’s position. The fish finder’s technology was initially employed in the 1990s and has been regularly improved since then. The technology of today’s fish finders has advanced to include modern technologies.

On the ship, there is a transmitter that broadcasts signals via waves. This SONAR technique utilizes echoes to return waves to the emitter. A signal is provided to the screen after the reflected waves are recorded.

The waves reflected from fish are shown differently from those reflected from stones, corals, or other impediments to ensure that the signals received are not misleading.

When there are fish in the water, echoes differ in size and shape from when the water is clear of fish. Different symbols are used to represent things other than fish. With the aid of a sign in the shape of a fish, the screen depicts a fish’s existence.

See also: The 6 Best Fishing Sunglasses Under $50

How to read a fish finder

Reading fish finders is difficult at first, but it is critical to master the skill before going fishing or being unable to utilize your gadget. Some fish finders are color-capable, while others are merely grayscale. Colors are used in fish finders to display information graphically. Items that are compact and solid will elicit a louder echo.

The color utilized on the screen will be bolder if the returned echo is powerful. The seafloor, or the deepest part of a waterbody, is sometimes depicted as the darkest object. Some technologies will be able to display a fish symbol for you. This is the scenario with Fish-ID technology, which transforms raw data into a graphical user interface.

Some of the most modern Fish-ID systems will show distinct icons for vegetation, stones, and fish schools. On the flip side, they are often inaccurate, misrepresenting weeds as a school of fish or a rock as vegetation.

Although arch fish finders are more exact, they provide raw data in the form of arches and lines. You will have to figure out how to interpret them on your own. Many anglers make the mistake of assuming that a long arch indicates a large fish. The length of the fish does not mean its size; instead, check the arch width to determine its size.

Arches can also be partly or full. A half arch does not imply that the fish is small. Remember, the width is the strongest indicator. There are many various models available, so study the fish finder handbook thoroughly before heading out fishing. You will need both knowledge and expertise to interpret the data correctly and locate and capture fish.

Read also: The 5 Best Portable Fish Finders

Various types of fish finders

Fish finders have grown increasingly significant as time has passed for everyone who wants to go fishing in the sea. Earlier, there were only just a few models of fish finders offered, but things are different, and there are now more upgraded models available, all of which are available depending on your needs.

When buying a fish finder, it is essential to understand the many types and features present. There are three basic types of fish finders:

2D fish finders

These 2D fish finders will remind you of something from the past; yet, they are rather conventional and straightforward to comprehend and operate. They have a black-and-white display, and with a reasonably typical scrolling technique, you can view pretty much anything below the water’s surface, including the soil, reefs, and any fish present at the time.

Recognizing fish from other items on this type of fish finder can be difficult, but it will not be an issue for you if you have a good grasp of digital equipment. Fish in this gadget are mainly identifiable by their bladder, represented by a dot or a dash; this makes it easier for individuals familiar with the device.

However, if you wish to utilize a 2D fish finder and have never used one before, bear in mind that you will almost certainly need some instruction or coaching with this type of monitor.

Down scan fish finder

If you are not a skilled angler, you may want to start small and avoid buying overpriced equipment, which is quite understandable, and this is where a down-scan finder kicks in. This is ideal for shallow waters since it provides a clear image of the water body, it is less expensive than other types of fish finders, and it functions well.

Any abrupt motion of the fish allows the angler to grab them since the detector goes off in a loud manner. The rough rocky surface is not visible in the finder, but the fish is pretty evident if you are interested in the appearance of the type of fish you intend to catch.

Side scan fish finder

If you are a professional fisherman or someone who enjoys fishing as a costly pastime, we are convinced that this type of fish finder will suit your needs well.

When you check the dynamism of this fish finder, you will realize that it is the most photorealistic that any fish finder can be. It only covers a small area surrounding your boat, but it spans it well and provides you with a clear picture of what is hiding beneath the surface. It has a range of 1 meter to 30 meters, capturing every fish it can discover in between.

This scanner is ideal for vast lakes and deepwater rivers; anyone who considers angling to be a luxury will adore what it has to offer. We emphasize the luxurious aspect since it will set you back a lot of money.

How to choose a fish finder

It is not easy to make a decision. You should think about the type of angling you undertake. It is best to purchase a fish finder with a large screen. The screens range in size from 3.5 inches to 16 inches. A 9-inch monitor is an excellent middle-of-the-range option. Check the pixels to ensure you have a high-quality image. A larger screen is less relevant if you plan to use it on kayaks. Choose a model that is both light and waterproof, or add a waterproof case.

How to install a fish finder

Regardless of how good your fish finder is, if you do not understand how to set it up correctly, you will not get the most out of it. These are the steps to take:


Like every other current tech equipment, it has its upgrades and information, and just like any other device, you need to register it by sending an email to the manufacturer. This way, they will know about the finder, and you will be able to get it rectified quickly if you run into any issues.

Update the software

If your finder is not updated to the latest model, it will create problems as soon as you start using it, and you do not want a foul finder that keeps getting you into trouble.

Find the perfect spot for set-up.

Ensure your fish finder’s panel is located where it should be: at the helm of your boat, at a location where you would ordinarily fish, and on higher ground so you can keep a close eye on it.

Find a power source

This device requires a constant power source; you will need a battery or a power generator to sustain the demand; it is recommended that you use a battery instead of a generator as it is a safer alternative.

Drill for cables and seal

You must drill and mount the number of holes required to install your finder. Use a high-powered drill to ensure that no fragments or other potentially harmful materials are left behind. Sealing these holes is critical since you do not want to lose cables, leading to additional troubles, such as an ill-fitting fish finder falling into the water.

Run the power

Examine the length of the wires to determine where they need to be trimmed, and ensure the cables are inserted as per colors and wire methods.

Set up wires for the transducer

A transducer is a gadget inserted into the boat’s lowest portion, and the SONAR technique tells you where the fish are. Before drilling and mounting the wires for the transducer, keep the following items in mind: do not mix the device’s wires with the engine wires, and ensure you apply sealant wherever it is installed.


Examine all of the fittings and all of the wires to ensure that they are correctly installed. Turn on the battery’s power and double-check that everything is in functioning order. If anything is not operating correctly, all you have to do is double-check the wiring connections.


Fish finders are essential equipment that enables you to locate fish rapidly and improve the quality of your angling excursion. They can be daunting to use at first, but if you are wary of returning home empty-handed, a reliable fish finder is worth investing in.

It will also allow you to learn from your blunders and comprehend what you are doing well or poorly when fishing. A fish finder will reveal why you catch fish in one area but not in another, helping you mimic the conditions that led to your success.

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