Fish Finder Buyer's Guide
2020 Edition

There are three key challenges that confront anglers seeking to catch fish. You have to entice the fish to strike your bait or lure, and you must set the hook and play the fish properly to get him up on the boat. But before either of these things matter, you have to overcome the first – and often most difficult – challenge the sport presents: Locating the fish.

Enter the fish finder.

How Do Fish Finders Work?

Fish finders are essentially sonar units. They emit high-frequency sound waves into the water, which then bounce off any solid objects in their path. The sonar unit collects these returning waves and processes them via a small computer circuit. This data is then translated into a visual representation of the water below. As the fish finder unit moves across the surface over time, the visualization scrolls across, creating an ongoing two-dimensional picture of what's under the surface.

In a nutshell, this process involves calculating the time it takes a sound wave to hit something and bounce back to the transducer. This allows them to determine the distance (depth) between the transducer and the object. Additionally, other properties of the returned signal, such as signal strength, allow the computer to determine some of the characteristics of the object. For example, a sonar signal that bounces off a rock will differ from one reflected off a weed bed or fish.

Different fish finders emit signals of different frequencies, and some fish finders emit more signals per unit of time than others do. Additionally, the computers and displays used in different fish finders vary in terms of quality and performance.  

Many fish finders work in conjunction with GPS data so that you can not only visualize what is happening beneath the surface but also determine your location in the water.

Fish Finder Categories

There are several different types of fish finders available on the market. And while any fish finder can help you catch more fish, you’ll want to select the best type of fish finder for your situation and needs.  

Conventional Fish Finders

Conventional fish finders typically perform one central function: They collect data about the world beneath the surface via sonar technology and then display this data on some type of screen in a way that is helpful to the angler. This helps you to learn more about the lake, river or ocean in which you are fishing, and it makes it easier to locate fish. 

Conventional units can usually provide anglers with information about the water depth, water temperature, major structural features and objects in the water, including vegetation, shipwrecks, sunken trees and any fish that are present.

The amount of detail displayed varies significantly from one unit to the next. Entry-level fish finders generally present somewhat crude images, while high-end fish finders present photograph-like images that are rich in detail. Some of the best units enable you to spot things like individual tree branches or clumps of vegetation.

Conventional fish finders are usually designed to be mounted on your boat, kayak or canoe, although some enterprising anglers elect to attach them to docks or other structures.

Flashers

Flashers are somewhat primitive sonar units, which typically display three key things about the water below: The bottom depth, the depth of your lure and the depth of any fish below you. While they don’t provide nearly as much information as most modern fish finders do, many anglers appreciate their simplicity. 

Most flashers display their data via a circular graph that correlates to the depth of the water. Objects within the beam of the sonar signal appear as lines along the edge of the circle. The placement of the line indicates the depth of the object.

Flashers are most popular with ice anglers, although they are also very helpful for those who like to use vertical jigging techniques in deep water. Many modern fish finders include a flasher function, which gives you the best of both worlds.

Dedicated flashers are typically designed to be portable, so that ice anglers can carry them around the frozen surface, as they move from one hole to the next. Some manufacturers offer optional “portability kits,” consisting of a padded travel case and a few other items to make the flashers easy to use, carry and set up.

GPS-Fish Finder Combos

GPS-fish finder combos are essentially conventional fish finders, which also feature a GPS circuit. This allows these types of fish finders to provide anglers with information about the watery world beneath their boat, as well as information about their location. 

GPS capabilities provide a ton of value for anglers. They allow you to mark (and later revisit) productive locations, they allow you to track your route through a lake or river, and they give you the chance to see a bird’s eye view of the waters, among other things. Most GPS-equipped fish finders also display your traveling speed.

Many GPS-equipped fish finders are also designed to work with plotting charts, which can provide even more information about your location and aid in navigation. While GPS capabilities were once a high-end feature only included in professional-caliber fish finders, most mid-level fish finders now offer GPS circuits.

Castable Fish Finders

Castable fish finders are small transducers that are designed to attach to the end of a fishing line. You can then cast the transducer out into the water where it will begin emitting sonar signals into the water below. These sonar signals bounce off various things in the water and are collected by the transducer, which then transmits the data to a hand-held display or smartphone.

Because they needn’t be attached to the hull of a boat, castable fish finders are most popular among shore anglers and those piloting kayaks, canoes and other small crafts. However, some anglers in traditional fishing boats like to keep one on hand, as they are useful for gathering data about difficult-to-reach pockets of water.

Because castable fish finders rarely come with a display unit, they are often very affordably priced.

Fish Finder Users

Anglers approach fishing in a number of different ways. Some fish directly from the bank, while others fish from canoes, kayaks or float tubes. Still others prefer to fish from traditional boats.

As you’d expect, these different fishing approaches require anglers to use different types of fish finders and to use them in different ways. And while there are no hard-and-fast rules dictating the types of fish finders different types of anglers should use, there are clear trends regarding the capabilities and features different anglers require.

Offshore/Inshore Boat Anglers

Most fish finders are designed for use with conventional fishing boats, so anglers who fish from boats typically have the widest selection from which they can choose. While a range of products certainly give offshore and inshore anglers great flexibility, it can make it difficult to sort through the numerous models.

Most fish finders are designed to work in either freshwater or saltwater, although some are clearly better suited for inshore anglers than offshore anglers, and vice versa. In general, the farther you fish from shore, the more you should prioritize fish finder power (which improves the depth range of the unit), GPS functionality and chart plotting capabilities.

Freshwater and inshore anglers, by contrast, are best served by prioritizing things like advanced imaging technologies and display quality. However, GPS capabilities and power are still important considerations.  

Note that sonar signals travel further in freshwater than in saltwater, and most manufacturers provide different depth ratings for the different types of water.

Some of the most important things offshore and inshore anglers should seek in a fish finder include:

• Deepwater capabilities so that you can find fish in several hundred feet of water. 
• GPS capabilities to pinpoint your location and allow you to mark waypoints.
• Chart-plotting capabilities to aid in navigation.
• Bluetooth or WIFI connectivity so that you can monitor your fish finder from anywhere on the boat.
• Radar functionality, which will allow you to see above-the-surface obstacles from afar. 

Kayak/Canoe Anglers

Anglers who fish from kayaks and canoes can often utilize the same fish finders as their conventional-boat-piloting counterparts can, but it is important that they use models that are well-suited for small crafts and small waters. However, kayakers who venture out into the sea will need to consider the same things inshore and offshore anglers do when making their choice in a kayak fish finder.

Some of the most important things kayak- and canoe-piloting anglers should seek in a fish finder include:

• Ease of installation and removal to facilitate use and storage of the canoe or kayak. 
• Side-imaging capabilities so that you can explore the water more quickly.
• GPS functionality so that you can determine your location and traveling speed.
• Excellent screen quality to help you see the display in bright sunlight.
• Map-making functionality for those who fish small rivers and ponds.   

Shore Anglers

Anglers who like to fish from dry ground have the fewest available options in the fish finder market. In fact, shore-bound anglers didn’t have any fish finder options aside from flashers for many years. However, a number of manufacturers have recently begun producing fish finders specifically designed for the unique needs of bank anglers.

Most bank anglers choose to use castable fish finders so that they can collect data on a variety of different locations. However, some anglers who like to fish from the shore prefer to set up a traditional fish finder, by attaching it to a dock or similar structure.

If you like, you could purchase a top-of-the-line fish finder with a multi-thousand dollar price tag and use it to fish from your local pier, but most of the unit’s advanced features wouldn’t be applicable to your circumstances. Accordingly, most bank anglers choose fish finders at very reasonable price points.

• Some of the most important things shore anglers should seek in a fish finder include:
• Wireless connectivity to allow you to view the information collected by the fish finder on your phone.
• Small size and to allow you to cast the fish finder as far as possible.
• Rugged housing to ensure the fish finder will withstand the wear and tear of repeated casts.
• Side-imaging capabilities to allow you to view more water (if you plan to mount a traditional fish finder to a dock).
• Map-making functionality if you prefer to fish small waters.

Key Fish Finder Terminology

Many anglers have difficulty wading through the copious amounts of jargon used to describe and distinguish between various fish finders. This can make it difficult to compare different models, and it often clouds the decision-making process.

Try to avoid these problems by familiarizing yourself with some of the most common fish finder terms listed below. Note that some of these terms are not specifically related to fish finders, but they are explained in the context of fish finding units. 

Click below for the full terminology list.

Features to Consider

Whether you fish from the shore, a kayak or a conventional fishing boat, you’ll want to get the best fish finder available at a given price point. This means you’ll have to compare the various features offered by different fish finders to arrive at the best choice.

The following features are some of the most important to seek when making your choice. You needn’t necessarily purchase a fish finder that provides all of the listed features, but you’ll likely want the most you can get for your dollar.

GPS Capability

GPS-equipped fish finders provide you with information about your location, as well as the objects under or beside your boat. This type of information is invaluable for finding productive fishing locations, navigating the water and scouting new waters. Most fish finders now come equipped with GPS, but some of the more economical, entry-level models and castable fish finders do not.

High-Quality Display Screen

It doesn’t matter how much data a fish finder collects if it can’t display this data in an easy-to-see manner. Accordingly, you’ll always want to select a fish finder that has the best display screen possible. Generally, this means seeking a unit that has a high resolution and produces color images.

Adequate Screen Size

While it is definitely important to select a screen with a high resolution and full-color images, it is just as important to select a fish finder with the largest screen possible. This not only makes it easier to view images when you are close to the unit, but it can make it possible to see the images while you are fishing at the other end of your boat.

System Flexibility

Most of the best fish finders allow you to customize the way the transducer collects information, which is useful for fine-tuning the unit, and the way this information is displayed. For example, some fish finders allow you to change the display colors, which can be helpful for maximizing the contrast and visibility displayed in poor weather or dim lighting, and most will allow you to select different types of data to display.  

Installation Type

Fish finders vary in both the way they are designed to be mounted to your boat and the degree of difficulty they present during the process. It is usually preferable to select a unit that is easy to install, but it is particularly important for anglers who must mount and remove the fish finder repeatedly.

For example, anglers who rent boats for fishing will want an easy-to-mount fish finder, as will those who fish from kayaks and canoes, as these types of boats are often stored between fishing trips.

Flasher

If you plan on vertically jigging in deep water or spending a lot of time ice fishing, you’ll definitely want a fish finder that includes a flasher function. The flasher function will eliminate any unnecessary information and allow you to concentrate on the fish and your lure.

Water Temperature Probe

Water temperature is a very important factor that influences fish behavior, so it is almost always helpful to select a fish finder that has a temperature probe inside the transducer.

Custom Map-Making Functionality

Anglers who fish large waters can usually find navigational charts that detail the lake or river in which they are fishing. However, those who fish in small farm ponds, rivers and creeks can rarely find maps or charts that provide the kind of detail desired. Fortunately, many fish finders provide map-making capabilities, which enable anglers to make their own custom maps on the fly.

Removable Storage

You’ll often find it helpful to take some of the information contained in your fish finder and transfer it to your home computer or a friend’s fish finder. Accordingly, many manufacturers make fish finders that utilize SD cards, which can be used to transport the data you collect.

Preloaded Maps and Charts

Some fish finders with GPS and chart plotting capabilities come with preloaded maps or charts. This prevents you from having to purchase separate maps for your device, and because some map packages are expensive, it helps to improve the relative value of fish finders that come with them.

Wireless Device Compatibility

Many modern fish finders are capable of connecting to other devices, such as your smartphone or tablet. This allows you to control your fish finder and view the images produced no matter where you are on the boat. It also allows you to transfer data (such as waypoints, navigation routes and custom maps) to your other digital devices. Most modern fish finders are compatible with both Android- and iOS-based devices, but it is still wise to verify that the one you are purchasing is compatible with your devices before you make your purchase.

The Bottom Line

It is easy to get overwhelmed by the number of fish finders on the market. There are a plethora of different models available, and the features and capabilities included in the different models vary widely. Additionally, the various manufacturers often use different terminology to refer to similar technology. This all makes it challenging to make apples-to-apples comparisons, and unfortunately prevents some anglers from obtaining the best fish finder for their needs.

However, if you carefully review the information and advice above, you can sort through the confusing language and select the best fish finder for your needs. Just remember to look for a fish finder that provides the features and capabilities that are best-suited for the style of fishing you enjoy, and be sure not to over-buy.