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Sonar for Ice-Fishing

By Bob Jensen - February 1, 2007
Open water anglers will usually admit that their most important tool for fishing success is sonar, which is often referred to as a depth-finder. Many anglers have a depth finder on the console of their boat so they can watch the depth and for fish-holding structure as they move around the body of water they're on, and another on the bow next to their electric motor so they can keep track of structure as they fish. A good sonar unit is just as important if you want to catch fish through the ice.

Just as in open water fishing, certain areas will be better for fishing through the ice. You need to find those areas. To do so quickly, many ice-anglers use a sonar that looks a lot like a flashlight. A good example would be the MarCum LX-i. When you get to your general fishing area, you want to pinpoint the area where you expect the fish to be. With the LX-I, you don't need to drill holes to check the depth. You simply squirt some water from a water bottle onto the ice and put the LX-I into the water. It will instantly show you the water depth directly below. You can quickly get an idea where the drop-offs are and how the structure is laid out.

Once you determine where you want to fish, you need to pop a few holes. As the ice-fishing season progresses, you'll want to drill more holes so you can cover more water faster. The Jiffy Stealth STX is a great unit for popping a bunch of holes quickly. It has specially treated blades that allow you to drill more holes without sharpening the blades.

"Just as in open water, sonar will help you catch more fish through the ice."
s Now that you're ready to fish, you'll want to drop the transducer of your sonar unit into the hole you're fishing. The sonar unit will show the depth, it will show your bait, and it will let you know if there are any fish down there. Modern sonar units are so sensitive that they will show your tiny jig and the split-shot you've attached to your line as separate targets, even if they're just a couple of inches apart.

The transducer sends a signal to the bottom that is like an upside down ice-cream cone. As the signal goes deeper, the area of coverage gets larger. Let's say you're over twenty feet of water. Your bait is directly below the hole and shows up as a bright mark. As you jiggle your rod tip, you can see the bait move.

Now, another mark of a different color shows up on the screen. It's moving toward your bait, and as it moves toward your bait, it gets brighter. When it intersects with your bait, you feel a light tap. You set the hook and a few seconds later a fish is flopping on the ice. Pretty neat stuff.

The reason the signal was a different color is that the fish was not directly below the hole you were fishing from, it was out to the side so the signal wasn't as bright. As it moved toward your bait, it sent back a more powerful reflection, making for a brighter signal.

MarCum recently introduced TrueColor into their LX-5 and LX-3tc sonar units. These three color units do a wonderful job of showing what's down there, and they're easy to use. If you're looking for an ice-fishing sonar, you should check these out.

Just as in open water, sonar will help you catch more fish through the ice. Watch it carefully as you fish and you'll be amazed at how many more fish it will put on the ice for you.

Author Bob Jensen
Bob Jensen
Bob Jensen is the host of the Fishing the Midwest television series, a series of television fishing shows that highlight fishing locations and techniques throughout the Midwest. He also writes a syndicated fishing column and does fishing seminars throughout the Midwest. He is a former fishing guide and tournament angler. Visit Bob's web site at
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