How Do Fish Finders Work?

Fish finders are relatively simple devices used to locate fish in the water. A display screen sits inside of your boat or mounts to it. The viewing screens come in various sizes with a range of configurations and options.

Although the screen shows you all the information you want to know, the transducer does all the work. The screen simply translates raw data from the transducer.

No time to read? See best selling fish finders from Amazon
SaleBestseller No. 1
Garmin Striker 4 with Transducer, 3.5" GPS Fishfinder with CHIRP Traditional Transducer
  • CLEAR VÜ SCANNING SONAR Shows you more of what is in the water around your boat; This high frequency sonar gives near photographic images with detailed representations of objects, structure and fish
  • THE POWER OF SIMPLE Offers a keyed interface with dedicated buttons; The device is easy to use and easy to install; Available in 3.5 , 5 and 7 inch display sizes; Water rating IPX7
  • WAYPOINT MAP Use the way point map to easily view, mark and navigate to locations such as brush piles, stumps and docks; Maximum depth 1,600 feet freshwater, 750 feet saltwater; Current draw at 12Volt : 0.23 Ampere
  • CHIRP SONAR CHIRP sends a continuous sweep of frequencies which provides a wider range of information; CHIRP sonar is able to create crisper fish arches with better target separation
  • BUILT IN FLASHER View your sonar data in the classic flasher format; ideal for ice fishing or vertical jigging.Display size: 1.9 x 2.9 inches (4.9 x 7.3 centimeter); 3.5 inches diagonal (8.7 centimeter)
SaleBestseller No. 2
Key Finder Pair, Indisputably the Loudest, Long Life Replaceable Battery, High-Impact Polycarbonate Case, and Two-Year Warranty
  • Loud, extremely durable, operates up to 300 feet, and battery lasts up to 18 months
  • Includes two KeyRingers - either KeyRinger calls the other
  • The KeyRingers are ready to use right out of the package - no setup or programming required
  • Great for families - if you order multiple sets of KeyRingers, they can all be called simultaneously or individually
  • Full 90 day, no-questions-asked, money-back guarantee and a totally free TWO-YEAR WARRANTY
SaleBestseller No. 3
LUCKY Handheld Fish Finder Portable Fishing Kayak Fishfinder Fish Depth Finder Fishing Gear with Sonar Transducer and LCD Display
  • ◆ Fishes and bottom contour readout: LUCKY fish finder portable detects and displays water depth, approximate fish location, short & tall weeds, sand & rocks on bottom. Fish finder portable design gives you another option to hang it around neck.
  • ◆ The kayak fish finder suits for variety fishes fishing environments: It can be used for off shore fishing, kayak fishing, ice fishing, lake fishing, sea fishing and so on. You can also use handheld fish finder on the moving kayak with speed below 5mph.
  • ◆Depth readout: The fish finder portable detector range is in a 45°cone underwater. The detection of depth range is from 3ft(1m) to 328ft (100m) below fishing sonar transducer. The water depth can be shown either in feet or meter. The fishing sonar sensor is with 25 ft cable and removable transducer float.
  • ◆ Small portable fish finder with powerful functions: 5 modes sensitivity options; battery save mode; backlight mode; fish and fish school alarm. Normally fishing depth finder supports 4-5 hours continuous working with brand new batteries. Open battery save mode can be working even longer.
  • ◆ Warranty Policy: We offer 12 months warranty for LUCKY fish finder portable. It will be one of your best fishing kayak accessories. Any questions before or after purchase, please feel free to contact us via Amazon message (response within 24 hours every day online).

The transducer mounts somewhere on the outside of the boat. It emits sound waves into the water to measure depth and size, which is then sent back to the display screen. These waves not only pick up on the floor of the water body but the objects within it as well. This includes logs, rocks, and other hazards.

Since these devices bounce off of everything they can reach, they could be useful in search parties and police investigations. If someone was last seen near a river or lake, the sonar could pick up on a human body as easily as logs and rocks.

However, recreational, amateur and professional fishers are the main users of this technology. Fish finders help them narrow down the location of the fish, how many there are, and their size. Additionally, these machines determine depth. Knowing the depth is important to search for certain species, in an unfamiliar location, or enjoy diving.

Although these features are important for all users, there are several others to consider when shopping – we will go through them later on.

Our Picks – Best Fish Finders of 2018

Garmin Fish Finders

Garmin is an impressive tech company that expands far beyond their fish finders. They produce watches, cameras, various smart technologies to track fitness and lifestyle, monitors and cameras for automotive vehicles, and flight decks for airplanes. If you can trust Garmin to fly you from LAX to O’Hare, you can trust them to help you find the tastiest catch.

Garmin STRIKER 5cv – Bang for Your Buck

Garmin fish finders

Garmin CHIRP technology
Ability to mark and share productive areas
Accurate readings over 1.000 feet
Complicated set-up made worse by lack of directions from the manufacturer

Value choice badge

Best Features:

  • Mounts anywhere on the boat
  • Displays boat speed and water temperature
  • Multiple options for viewing screen
  • Optional carrying case and upgrades

This product and many other Garmin fish finders utilize their CHIRP sonar technology. This sends continuous sweeps of varying frequencies to give you more information. You’re able to improve this already impressive transducer up to a GT22 or GT23. Without upgrading transducers, you receive results from depths of 1,100 in salt water and 2,300 feet in freshwater. The greater range of information this machine is capable of providing can be seen on its 5-inch display screen. Additionally, a portable, waterproof carrying case and rechargeable battery come with this product. It also comes with transducer mounts for ice-fishing, fixed mounts for small watercraft, and a trolling motor mount.

Check the Price

Garmin echoMAP CHIRP 43DV – The Affordable Favorite

Garmin echoMAP CHIRP 43dv fish finder

Garmin echoMAP CHIRP 43DV
Garmin CHIRP technology
Dual-frequency sonar
Sonar recording and sonar history rewind
Protective cover sold separately
Manual is not specific to the product

Best Features:

  • Easy to install and use
  • Comes with US LakeVu charts
  • Compatible with BlueChart g2, BlueChart g2 Vision, or LakeVu HD Ultra

Don’t confine your love of fishing to the same waters. With this Garmin product, you can conquer any aquatic territory! Garmin’s CHIRP technology teams up with pre-loaded LakeVu maps, providing immense detail of what’s beneath you.

If you choose to improve the already remarkable results, the device is also compatible with upgraded versions of LakeVu and BlueChart g2.

The convenience of this device is further highlighted by available tide tables and water temperature logs. Additionally, it offers two different mounting options. They key is simplicity. It’s very simple to setup and use, making it one of the best fish finders for first-time users.

Check the Price

Humminbird Fish Finders

Since their first day of business nearly 50 years ago, Humminbird has never lost focus on the needs of fishing enthusiasts and professionals. They continually innovate the realm of GPS, sonar technology, navigation, and cartography. You can put your full faith into a Humminbird fish finder because they pour their endless devotion to angling in every device.

Humminbird ICE-55 – The Ice Fisher’s Best Friend

Humminbird fish finders

Humminbird ICE-55
Comes with a carrying case
Interference rejection in its own frequency
Dual beam transducer
Battery included
Cords and float are setup together with the transducer
No GPS or chart plotter

Best Features:

  • Extreme temperature LCD
  • Various cone angles from which to choose
  • Seven different depth scales
  • Six-color display for the colorblind or those sensitive to color

This Humminbird fish finder is ideal for ice-fishing, other hard waters, and extreme temperatures. Its fiber optic ice flashers and backlit LCD offer accurate, real time sonar displays. This makes finding digital depth a breeze. Additionally, the six-color LCD also aids those who are colorblind or sensitive to color.

Don’t worry about losing track of your schedule either! The battery display allows you to track how many hours of fishing you have left before it dies.

This is one of the best fish finders to save time by avoiding dense ice spots. Although there is no chart plotter to mark waypoints where ice is thicker, it makes the device more affordable. If you want to enjoy your winter fishing, you need this fish finder.

Check the Price

Humminbird 859ci HD – No Compromises

Humminbird 409120-1 859ci HD fish finder

Humminbird 859ci HD
Easy to read dual display
Easy to use
Built-in GPS
High-tech processor quickly displays temperature/speed/time
Difficult to setup without mapping software
Topography of lake not available without additional software
Comparatively heavy

Premium choice badge

Best Features:

  • Ethernet capabilities
  • DualBeam PLUS with SwitchFire sonar
  • 7-inch screen

Although the price might make you cringe, this is ultimately the best of the best for serious anglers who want to make no compromises whatsoever. It high speed processer with 360 imaging and I-pilot link compatibility. The GPS-Sonar combo on this Humminbird fish finder utilizes Dual Beam PLUS with SwitchFire.

You can clearly view the results of this high-quality technology on a large 7-inch screen and 480 x 800 color resolution. The backlit LCD shows crystal-clear images, even in the harshest of sunlight. There are even dual SD card slots for advanced cartography and saving screenshots, way points, and sonar recordings.

This is the best fish finder for professionals or otherwise experienced fishers. This device will take you to the next level. If you think you’ve already met your fishing potential, let this device prove you wrong.

Check the Price

What Features Should You Look For?

Transducer Frequency Range

Transducers do most of the work, sending and receiving sonar waves. Mount to the boat, waves bounce off surfaces below then back up to create a map on your display screen.

There are three types of transducers:

High frequency

These transducers have more wave cycles per second, but shorter wavelengths. These work best in shallow to moderately deep waters for spotting smaller fish and greater detail of what’s around you. Choosing an 800 kHz or 455 kHz transducer will provide the best resolution.

If you want to see deeper into the waters, avoid a high-frequency transducer.

Low frequency

These transducers have fewer wave cycles per second, but longer wavelengths. They work best in deep waters for spotting large fish and structures where fish may hide. The picture is less clear but operates well enough for fishing in the ocean.

If you typically fish in smaller waters, a low frequency is not necessary.

Dual frequency

Most fish finders utilize dual-frequency. They emit and receive more than one frequency at the same time for more accurate results. There are also Dual and QuadraBeam transducers that emit multiple frequencies in different directions.

If you fish in several types of water and require more accurate results, dual frequency might work for you.


The power measures the strength and speed of the sonar waves. Higher wattage equals deeper, quicker readings, while lower wattage equals slower waves and results.

Deep sea fishers should look for at least 500 watts although 1000 watts or higher would be more suitable. If you normally fish in shallower water, shelling out the money for higher power levels would be futile.

Screen Resolution

The higher the resolution, the more pixels are on your screen. A larger number of pixels results in sharper images so more detail can be seen. If there are more pixels on your horizontal axis, objects remain onscreen longer.

Regardless of where or how you fish, this is a feature to watch when browsing the best fish finders. You definitely get what you pay for with this one.

Screen Color

Just like our televisions, the best fish finders have color display screens. Some black and white models still exist but aren’t preferable unless they are the only options within your price range. Reading your screen is much easier with hundreds of shades of different colors rather than hundreds of shades of grey.

Some color screen fish finders have options to change the color scheme of your display. If you are color blind, sensitive to color, or have other problems with vision, this option is of great benefit for you.

GPS and Chart Plotters

Some devices come with a built-in GPS. However, a traditional GPS can only tell you the coordinates of your location. A chart plotter also determines your location but is capable of employing integrating it into more advanced applications.

It marks your location on a map, allowing you to view the surrounding area, set destinations, and view traffic conditions.

A chart plotter is especially useful for large boats or anyone in the ocean far from bay. It ensures your safety by helping you stay on the proper course. It is still helpful in smaller bodies with which you are unfamiliar or to improve your game in tournament fishing.

The Final Say

It’s easy to get confused by all the seemingly endless options for fish finders on the market. However, it’s simple once you figure out how you will use your fish finder and what features you need most.

Despite what features you require, there are Humminbird and Garmin fish finders for every type of angler. They continue to maintain the devotion and trust from their customers that they reciprocate in the quality of their products. They work hard to bring you only the best and most progressive technologies that make doing what you love more convenient.

Whether you prefer fishing in the deep-sea, hard ice waters, winding rivers, or your local lake, the varieties available expand across all fishing specialties and general use. Whatever you require, it’s easy to find these trusted brands at relatively affordable prices.

When it comes to the best fish finders, you definitely get what you pay for. Don’t let cheaper brands fool you into spending money on a device that doesn’t satisfy your needs.

If you want a long-lasting fish finder that will improve your game, you are in the right place to start browsing. Stop fishing the traditional way or using an outdated fish finding device. If you really want to pull the competition out of the water, you need Humminbird or Garmin fish finders! They are some of the best fish finders on the market!

Not only will it make fishing more enjoyable, but you will easily make your money back with huge loads of fish you bring back to the dining table. Just don’t tell your wife or your friends about the secret technology that upgrades your fishing abilities! If these models are out of your budget, be sure to read our review of cheap fish finders also.