Different Types Of Fish Finders (Explained For Beginners)


by Robert Ceran

Fish finder technology has improved dramatically over the past 15 years, resulting in a wide variety of fish finder types that provide many different ways to view the underwater world.

But having all this sonar technology available can also make it challenging for a beginner to get an accurate overview of the different types of fish finders, and what they can be used for.

In this article we’ll walk you through the main types of fish finders, and will cover their key strengths and weaknesses.

We’ll also give you our tips on how to choose a fish finder, so you can decide what type of fish finder works best for your purposes.

What are the different types of fish finders?

The main types of fish finders are as follows:

  • 2D sonar
  • Side imaging fish finder
  • Down imaging fish finder
  • Live sonar
  • 360 imaging sonar
  • 3D fish finder
  • Chartplotter fish finder
  • Ice fishing flasher
  • Castable fish finder

With that being said, most fish finders nowadays combine several of the sonar technologies listed above in a single unit, and it’s rare to get a fish finder that only comes with one type of sonar.

We’ll also cover CHIRP sonar, which technically isn’t a separate type of fish finder, but rather an improved type of sonar that’s used in the majority of fish finders nowadays.

What is a fish finder?

A fish finder is a sonar device used by anglers to locate fish in the water column, view bottom structure, and measure water depth.

Fish finders use a transducer to transmit sonar waves into the water, and then interpret the resulting sonar returns to generate an image of what’s in the water underneath the boat. 

Fish finder vs depth finder – what’s the difference?

The main difference between a fish finder and a depth finder is that a depth finder only provides information about water depth, while a fish finder in addition provides information about bottom structure, objects in the water, as well as fish. 

The read out of a depth finder only shows a number that corresponds to water depth, while fish finders in addition show a graphical representation of the bottom and everything in the water column.

In high end fish finders this can provide enough detail to allow you to identify individual fish. 

Different types of fish finders explained

Now let’s take a closer look at each of the main fish finder types, to get a better understanding of what they are capable of. 

2D sonar

2D sonar is the oldest type of fish finder technology, and is thus often called traditional sonar. 2D sonar uses a round transducer that shoots a sonar cone down into the water which widens as it travels through the water.

While 2D sonar has lower resolution than other types of sonar, it comes with the advantage that it penetrates deeper into the water than either side imaging or down imaging, and so is the main type of sonar used by deep water anglers targeting water over 150 feet deep.

Down imaging fish finder

Similar to 2D sonar, a down imaging fish finder also works with a sonar beam shot straight down into the water, but unlike 2D sonar, its sonar beam is very thin, and doesn’t widen as it travels down through the water. 

Because of its narrow sonar beam, down imaging shows a narrow cross section of the water and the bottom straight underneath your boat, and thus generates a very high level of resolution.

In addition to this, down imaging usually uses shorter wavelengths of 455 or 800 kHz, generating much higher target separation, further contributing to its higher resolution.

Down imaging is great when you are fishing on top of structure, as it allows you to see every single detail with high resolution, including any fish that are in the area. 

Side imaging fish finder

As the name suggests, a side imaging fish finder uses a transducer that shoots two sonar cones sideways on each side of the boat.

Due to this setup, side imaging can cover large areas of water up to 240 feet on each side of the boat.

Similar to down imaging, side imaging uses short wavelengths of 455, 800, or even 1200 kHz. These high frequencies are great for generating high resolution images, but don’t penetrate well into deep water.

Side imaging is ideal for scanning large areas of a lake in order to find fish holding structure, which is why it’s also often referred to as structure scan.

Once you find interesting structures with side imaging, such as rock piles, trees, or ledges, you can then investigate these spots in more detail with either 2D or down imaging. 

CHIRP sonar

CHIRP sonar is technically not a separate kind of fish finder, but actually an improved version of sonar that is nowadays used by the majority of fish finders, including most entry level models.

While traditional sonar uses a single wavelength (such as 80 or 200 kHz), CHIRP uses several wavelengths at the same time, which helps to eliminate inaccuracies that arise when using a single wavelength.

CHIRP is currently the industry standard for most 2D, side imaging, and down imaging fish finders, and helps to make them more accurate. 

Live sonar

Live sonar is one of the most recent sonar technologies, and shows sonar returns that are updated in real time. This is very different from other types of fish finders, which usually show an image consisting of historical sonar data. 

Live sonars (such as Garmin LiveScope, Lowrance Active Target, and Humminbird MEGA Live) have taken the fishing world by storm, as they allow anglers to see fish, as well as their lure, in real time, which has coined the term “video game fishing.”

While live sonars aren’t good for scanning large areas in search of fish holding structures, they are great when you do find fish, as you can see exactly where they are, and how they react to your lure or bait. 

360 imaging sonar

360 imaging is similar to side imaging, but instead of relying on sonar beams that are transmitted sideways, it consists of a transducer that rotates 360 degrees, and thus scans in all directions surrounding your boat. 

360 imaging is great when using spot lock in relatively shallow waters, as it allows you to see structure and fish in all directions.

It’s like having side scan even when you’re not moving (which is in contrast to side imaging, which only works when your boat is moving).

3D fish finder

A 3D fish finder uses a software algorithm to combine data from a side imaging transducer into a 3D image, which makes it easier to get a clear picture showing how fish relate to structure.

This is different from other fish finder types, which generate a 2D image that you then need to interpret in order to extrapolate 3D information.

However, while a 3D fish finder certainly creates very impressive images, it doesn’t provide you with as much of an advantage as most people think, and in my opinion doesn’t really justify the extra cost. In general, I would always recommend live sonar over 3D sonar.

Ice fishing flasher

Ice fishing flashers are designed specifically for vertical fishing, and similar to live sonar, they show sonar returns that happen in real time.

In other words, you won’t see any historical data of fish that passed through your sonar cone a while ago, but only signals corresponding to fish that are there at this instant. 

The nice thing about ice fishing flashers is that you can often see both your lure and fish as they come in to mark the lure, which is very exciting to watch.

In recent years, a number of fish finder brands have developed ice fishing fish finders that generate almost identical results to flashers, and which can be used interchangeably.

Castable fish finder

Castable fish finders are wireless fish finders that can be cast out from shore, and that float on top of the wate, with their sonar scanning what’s underneath them in the water.

In most cases, castable fish finders communicate via bluetooth with a smartphone or tablet, and provide a cost effective way for shore based anglers to take advantage of fish finder technology. 

Chartplotter fish finder

A chartplotter fish finder combines sonar capabilities with advanced mapping capabilities that allow you to upload lake maps and then check your position on them with GPS.

In many cases, chartplotters also allow you to create your own custom maps, and to refine lake maps with your own sonar data. 

However, the distinction between regular fish finders and chartplotters has become blurred in recent years, since even entry level fish finders often come with mapping capabilities nowadays.

Mapping is a great option if you want to explore a new fishery, or if you’re fishing on a big lake, where it can take a long time to find the best fishing spots without a map.

What is the easiest fish finder to use?

The easiest fish finder to use is currently the Lowrance HOOK Reveal, which can be used out of the box with factory settings that are pre-optimized for most fishing applications.

In addition to its ease of installation and use, the HOOK Reveal TripleShot comes with an all-in-one transducer that gives you access to 2D sonar, CHIRP, side imaging and down imaging in one unit.

Finally, the HOOK Reveal also comes with Fish Reveal technology, which makes it easier for beginners to spot fish. 

What type of fish finder should you choose?

The best way to choose a fish finder is by deciding what sonar technologies you’ll need, as well as the size of your budget.

If you’re a beginner, it’s generally best to get an entry level unit (such as a Garmin Striker or Lowrance HOOK Reveal), since these are designed to be easy to use straight out of the box.

In terms of sonar technologies, I would recommend an entry level fish finder that comes with 2d sonar, down imaging, and side imaging capabilities, combined with an all-in-one transducer that covers all of these options.

Lowrance HOOK Reveal, Garmin Striker Vivid, and Humminbird Helix all come in variants that have all these features and that retail around 500 dollars.

If you’re on a tight budget however, you can also opt for a fish finder that only has 2D, or just 2D plus down imaging sonar.

But if at all possible I recommend adding side imaging into the mix, as that really helps when scanning large areas to find fish and structure.

Finally, if you also want to get your hands on mapping capabilities, the most advanced entry level units usually come with that option, though that will tend to drive your price up a bit.

If budget is not an issue for you, you can opt for a larger unit, such as Lowrance Elite FS, Garmin Echomap, or Humminbird Solix right away.

The nice thing about all these units is that they give you the option of adding live sonar at a later stage.