Reading a Fish Finder how to guide

Reading a Fish Finder Screen: How to Do it Easily

If you step on a fishing boat today, there are high chances that you will find it equipped with a finder. This is meant to help the angler maximize his efficiency and end up with a boat full of fish.

However, in most instances, the anglers have no idea what they are looking at on the screens, beating the very essence of having the gadgets on board.

We don’t want you to fall in this category and will teach you how to interpret the information presented on the fish finder screens.

Stick with us to the end to find out more.

How Fish Finders Work

Fishfinders feature a transducer that relies on sonar technology to enable you to know what is below your vessel. This technology shoots sonar signals to the bottom of the water body and back up, thereby providing you with the information you need.

The signal is not sent as a straight line but in the form of a V-shaped sonar cone. Then, the sonar beam is pretty narrow, providing a spotlight of about 10ft. For this reason, the only information you’ll get will be about whatever is directly underneath your boat.

Sonar cone

Once the pulses that the transducer has released hit an object, they are thrown back up for the receiver to interpret them. Then, the results will be displayed on the screen.

Sometimes, the fish finder could be too sensitive such that it picks up more than you need. So, you should adjust the sensitivity to ensure that it only delivers the signals you need.

The Fish Arches

Whenever a school of fish passes through the sonar cone, they will be displayed on the screen as arches. Note that at times, the fish will show up as dots, and this mainly applies to down imaging. This is because the sonar spotlight is narrower than average, thereby only displaying a small portion of whatever is underneath your vessel.

That being said, with time, you should be more accurate in using the arches and dots to determine whether it is a fish or a school of fish close by.

What About the Size?

For most fish finders, larger arches signify larger fish. However, there are other things about the arches that could tell you the size of the fish. This includes their shape, width, and thickness. Additionally, you can also use the height of the arch on the screen to determine how big or small the fish is.

If a fish is presented on the screen as a full, curved, and thick arch, know that it is a big one. On the other hand, a smaller fish will appear in the form of partial patches that are slightly thinner and not as curved as their counterparts.

All the information we have presented above relates to fish finders in general. How about we now look at reading specific brands?


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I) How to Read Garmin Striker 4 Fish Finder

How to read a Garmin Striker 4 Fish Finder

The operation of the Garmin Striker 4 device is not that different from other fish finders in the market. It acts in the normal way whereby the transducer sends sound waves into the water, and when they strike an object, they return to the transducer.

After that, the soundwave data is processed by the receiver and converted into the image displayed on the screen.

Another thing you ought to know is the significance of the different portions of the screen. All the information appearing on the left-hand side represents fresh or recent data, while the left side is where you find what the system picked up sometime back.

The other significant factor you ought to know is the colors where strong signals appear yellow while the weaker ones are shown as blue and red.

Why Fish Appear in Arches

By now, you must know that fish appear on the devices as arches, but do you know why? Let us spell it out for you.

When the transducer sends out signals, it does so in the form of a cone. And if you draw a line from the transducer, you’ll notice that the ones on the extreme are longer than the middle lines.

So, when the fish swims across the sonar cone, the time taken to reach the soundwave is longer, and as it moves deeper into the cone, the return time reduces before rising again. All this will present itself in the form of arches, as you shall see on the screen.

II) Reading a Lowrance Fish Finder

Reading a Lowrance fish finder screen

The impressive bit about reading the Lowrance fish finder is that it is a fairly straightforward process that aims to enable you to maximize your fishing venture. First, just like most other fish finders out there, you can tell the size of a fish by looking at the color and thickness of the arch.

Next, this device stands out with its own imaging, which pays more attention to the object rather than its surroundings. This aspect will be pretty handy when locating fish in an area full of weeds and other vegetation.

This fish finder also has a side scan, only that it is problematic to identify fish in a rocky bottom. So, side-scanning would only work when dealing with a soft bottom as the fish will have a hard time hiding.

As if that’s not enough, there is the 3D Structure Scan that provides you with a clear picture of the fish in the water. This feature is particularly useful when attempting to catch suspended crappie.

The Trackback Feature

At times, you may not be sure what you have seen, and you need clarification. In such an instance, the Trackback feature will help you out a lot as it gives you the option to view an image once more. This will help you accurately pick out the spot where you may have seen your potential catch.

The Insight Genesis

This is a cloud-based program through which you can create comprehensive contour maps that would give you an idea of how the water body’s bottom looks like. With this picture, it will be easier to identify the spot where the fish are hiding.

You could either access the basic features for free or subscribe for advanced features at the cost of $99.

III) Reading a Humminbird Fish Finder

Humminbird fishfinder screen reading

You do not have to be a tech-savvy individual to use the Humminbird fish finder as it is pretty easy to use. The friendly user interface will ensure that interpreting the information displayed on it is a walk in the park.

Once the device is on, the information on the screen could be on various subjects, such as the water depth or temperature. Note that the digital readings are affected by the positioning of the transducer sending pings into the water and back.

The Bottom of the Water Body

The factor that you ought to pay attention to at the bottom of the screen is the line crossing it. A thick dark line tells you that the bottom is hard, while a thin light one indicates a soft one.

Then, you’ll also note other lines or objects protruding from the bottom line up, representing vegetation or rocks that have been submerged. And if the lines are too close to each other, that points out the objects’ density in the water.

The Fish

Depending on the Humminbird model, the fish are either represented by arches or fish icons. Whenever a fish crosses the sonar’s spotlight underneath your boat, an arch or sonar will be displayed on the screen.

Keep in mind that the length of an arch does not translate to the fish’s size. Instead, it indicates the length of time that the creature has spent under the sonar. For this reason, a longer arch implies that the fish passed through the sonar slowly and for a longer time.

On the other hand, a shorter arch means that the fish passed the sonar quickly.

What do we learn from this? If you want to boost your chances of having a successful fishing session, look out for the bigger arches, as this presents you with the perfect opportunity to catch the slow-moving fish.

IV) How to Identify Bass Using a Fish Finder

When it comes to differentiating bass from other fish species on your fish finder, there are some basic rules that you need to follow. However, you need to have prior experience interpreting any information presented on the device’s screen.

With that in mind, here are a few tips on how you can identify bass species for a straightforward bass fishing venture:

*The size of the dots

First, the size of the dots showing up on your device’s screen is determined by its sensitivity levels. When the levels are low, smaller dots will show up and vice versa. So, we advise that you adjust it to medium levels to get the best and accurate results.

Then, press your ballpoint pen against a piece of paper to get an idea of the size you are looking for on the screen. If the dots showing up on the screen are equivalent to that on the paper, that is an indicator you are looking at bass fish.

*Space Between Dots

The other hint you should look out for is the space between the dots. When you think about bass fish, liken them to introverted individuals who value their spaces away from other people.

This should tell you that you should expect the dots to be at a further distance from each other, roughly 1cm to 1.5 inches apart.

In case you spot dots that are too close to each other, know that you are looking at another fish species in the saltwater body.

*The Spread

Another way of identifying bass fish on your device is by looking at how the dots are spread at the bottom. Bass fish tend to spread more horizontally than vertically, plus they are not as tall as other species.

If you spot dots that are grouped vertically, it could be other species such as crappies.


Regarding side and down imaging, extremely low boat speeds will lead to poor-quality photos. You will note that the images get distorted at speeds of less than 2mph, and it will become impossible to interpret the information presented on the screen.

How Much Area Does the Fish Finder Cover?

Since the spotlight from your device’s transducer beams out as a cone underneath your vessel, it will cover a wider area as it goes deeper. If you are familiar with the shape of a cone, it is easy to picture how the sonar expands with an increase in depth.

The cone’s angle will be determined by the sonar’s operating frequency, where a higher frequency will lead to a narrower cone.

Other Tips to Getting the Most out of Your Fish Finder

As we conclude, we shall provide you with some tricks that you may use to get the best performance from your device. They include:

*Regular Practice

The more you use a fish finder, the more you will understand how it works. This way, you can easily know what you are seeing and interpret the information presented more efficiently for the sake of maximizing your catch.

*Adjust the Sensitivity

Next, if your transducer is picking up too much irrelevant stuff, this implies that the device is too sensitive. In this instance, it would be wise to reduce the sensitivity to a level that would remove all the clutter from your screen.

*Read The Manual

Take your time to read the user manual that the device comes with so that you know the different features and how they can help you have a successful expedition as an angler.

*Study the Fish

Lastly, do some research to understand everything regarding your target fish fully. This includes their ideal temperature the breeding, and feeding habits. With this information at hand, you will eliminate guesswork from the equation and narrow it down to your target more easily.

Final Thoughts

From a distance, the fish finder’s screen may seem to be a very strange thing. However, as presented in this article, you can easily interpret all the data appearing on the screen. This way, you can tell the species close to your boat and how the bottom of the water body looks.

Now that you know how to read the fish finder’s screen, you are sure to end up with more fish in your boat at the end of the day.

Erick Thompson

Hi, I'm a fishing & kayaking enthusiast who enjoys sharing tips and tidbits with newbies, intermediates, and experienced anglers alike.

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