How to Read a Fishfinder: Step by Step Guides

As fishing has become popular throughout the years, technologies developed equipment to make our fishing trips easier and more enjoyable. Nowadays, technology allows us to locate large fish schools and also to know the condition of the water bottom.

A fish finder is a portable and handy device and most importantly, very valuable. Fish finders are essential if you want to have bigger chances of catching a large number of fish by showing you the exact location of the fish as well as finding obstacles. 

No matter how impressive the fish finder you buy is, it will not be very useful unless you learn how to read the screen properly to make the best of your fishing trip.

How to Read a Fishfinder: Step by Step Guides

1. Choosing the Fish Finder

How to Read a Fishfinder

One thing to bear in mind while choosing the fish finder you will use on your trips is that they either come in color screens or grayscale -black and white- screens.

A color screen will allow you to see the strongest signals as they present them in darker colors. So, if the transducer returns a stronger signal, the fish finder will display it in a darker and stronger color.

2. Understanding How the Display Works

As a fisherman, you will need to have a clear view of what’s underneath your boat so you can make the best of your fishing trip by gaining more insights into your surroundings. Not only does a fish finder allow you to locate the fish but also it shows you how the fish responds to your bait. 

Fish finders mainly use sonar to create a displayable image of the area in which you choose to fish, by shooting a beam in the water, it gives you a small amount of bottom coverage. Which allows you to read the screen sonar efficiently. 

3. How Do You Identify The Fish on The Screen?How Do You Identify The Fish on The Screen

The main purpose of using a fish finder is to identify the locations of the fish. Some fish finders have a fish-ID technology, which allows you to see simplified data in a user-friendly interface.

This offers you the opportunity to see the fish below you displayed on the screen in all their different lengths and sizes in addition to identifying schools of fish and obstacles like rocks or plants. 

Generally, there are three types of screens: traditional transducers, side imaging and down view imaging, or fish finder and chartplotter combo.

  • Fish Finders with Traditional Transducers

Most fish finders with basic features and screen will typically display two numbers on the top right to show two critical readings: the depth of the current reading and the water temperature.

The temperature only shows up if the transducer has a built-in temperature sensor, however, so make sure you know if your fish finder comes with one.

Moreover, you could find reading for speed, either in mph or kph, available on some models. 

A red wavy line going through the screen represents the bottom while a green one would indicate a soft bottom. If your sonar waves hit a very hard bottom, that would be represented with one deeply colored line and nothing below it.

Finally, you could find little images sticking out of the bottom which would indicate a sort of structure. That’s a good sign because fish usually like to hang around structures for protection. If you find any arches on top of the structure, there’s a high chance that these would be gamefish.

  • Side Imaging and Down Imaging

Down Imaging, or DownScan, works from right to left like a traditional SONAR. However, Side Imaging works from top to bottom, where the top-most item is your boat and everything below that is what you just passed over.

Somewhere on top, you’ll find the depth of the water and on the bottom you’ll find speed and temperature.

A down or side-imaging fish finder works with very high frequencies, so the pictures it shows are a lot clearer.

The line you’ll see going through the middle of a Side Imaging finder would represent the surface of the water. On each side, you’ll find a deep blue that represents water level, and the light purple represents the bottom.

It’s worth mentioning that some fish finders give you the option to change the color scheme, so you can use a brown or green one instead of the standard blue.

If you notice a shadow somewhere, it would probably be a couple of trees. They appear as shadows because they represent areas that the sonar couldn’t reach, so they show up as voids, or more commonly, shadows.

Fish are represented as dots, where the size of the dot reflects the size of the fish. Once you find a structure though, you should be extra cautious because this is where gamefish are normally found.

Generally, down or side imaging finders are much more accurate than regular fish finders and they display way clearer and sharper images.

However, they’re limited to 100 or 200 feet deep, which isn’t that deep. So, it’s not ideal for sea or ocean fishing.

  • Fishfinder/Chartplotter Combos

This combo offers increased screen real estate and allows you to divide the view into two -sonar readings on one side and navigational charts on the other. By combining the two views, you can even mark viewpoints at places that you find interesting.

Some enable you to superimpose a structure onto the map so you can see your boat going through said structure. This makes it seem as though your boat is navigating the underground troughs and peaks as it moves along them.

4. Understanding Fish Arches on Your Fish FinderUnderstanding Fish Arches on Your Fish Finder

The perfect fish arches are the ones that return a stronger signal on the screen displayed in thick marks. The bigger the fish, the thicker the mark on the screen will be. In most cases, the short, thick mark on the screen means that the fish is large. While the long, thick mark means it is a small fish. 

The most important and tricky part in identifying fish arches is identifying the right arches. You need to make sure that the fish completely moved across the diameter. In case they didn’t move entirely across the diameter cone, it’s a false alarm, there will not be any fish arch.

The most common thing to see on a fish finder display is a false fish arch, which appears as a half-arch. In this case, the fish probably only went through one part of the transducer cone.

With a little experience with using fish finders, you will have a better picture of the structure and the size of the icons you see on the screen and accordingly classify fish according to their sizes and locations. 

5. How to Spot a Large Fish on the Fish Finder

The best way to locate a rewarding fish on the fish finder is by checking the width and thickness of the fish arches displayed. Even though it might not be necessarily a full arch, but the main thing to look for is a thick arch. 

This is a simple yet, efficient way to locate your bigger targets and to make the best of your fishing trip.

6. Importance of the Depth Finder Feature

Depth finders are also helpful to identify the depth of the water underneath you in addition to detecting the temperature of the water which helps to identify the type of fish you should expect in that fishing spot. 

You can find the depth finder feature on the fish finder top left corner of the screen. Depth finders use meters as a scale of measurement instead of feet.

7. How to Get an Accurate View of the BottomHow to Get an Accurate View of the Bottom

The beam coverage plays a huge role in spotting targets. To make the best of it, you need to learn the advantages of both wide beam and narrow beam coverage.

A wide beam can cover a large area but on the downside, it provides less bottom detail. On the other hand, a narrow beam covers smaller areas but offers you a more precise bottom identification.

A narrow beam can also help you identify a better reading of the shelves and humps than the wide beam can.

  • Vegetations And Plants

Sometimes, a potential good fishing spot could be in a plant and vegetation area. In which case, your fish finder will have a displayed signal of vertical lines or spots. 

  • Depressions

Spotting depressions using fish finders is very efficient and easy. Simply search for a small v-shaped dip at the bottom of the water while reeling.

  • Identifying Unknown Objects

All objects are different in size and shape. But you can never have an idea of what exactly is underwater. What you can do is get an idea from the shape of the object displayed and how strong their returned sonar was. 

Identifying underwater objects is also very helpful to give you an idea of how soft or hard the bottom is.

Final Thoughts

You must be excited to go fishing. To make sure you have an enjoyable trip, ensure you have all the knowledge needed on using important supporting tools such as fish finders. Not forgetting to pack lightly and to always take safety precautions.