Plenty of anglers need a portable fish finder. Whether that’s because they fish from the bank or rent a canoe or kayak, they need electronics that are truly portable, not just demountable.
You’ll see recommendations for “portable” units that require drilling to mount or demand an external power source. Neither of these will work for you unless you own your own boat.
But if you’re a bank angler or small boat renter looking for an option that you can carry with you with minimal fuss, for us, that means an internal power source rather than a heavy 12v battery, and that cuts the competition down to castable units that rely on a paired smartphone.
Don’t worry - with improvements in castable electronics, you don’t need to feel outgunned by anglers using mountable alternatives. Below, you’ll find reviews of our favorite portable fish finders and a complete buying guide that demystifies the tech.
Quick glance at the best portable fish finders:
Table of Contents (clickable)
Maximum depth: 330 feet
Maximum range: 330 feet
Transducer beam angle: 7, 16, and 47 degrees
Frequency: 100 kHz, 290 kHz, and 675 kHz
Target separation: .4”
Compatibility: iOS 12.0 and Android 5.0 forward
Battery life: up to 8 hours
Charging time: 75 minutes
Deeper knows that castable tech can’t equal expensive mounted fish finders like those from Humminbird, Lowrance, and the like Garmin. But they also know they can close the gap, offering tech that’s darn near as good.
Their CHIRP does just that. Take the already capable Pro+, further improve the transducer, add awesome CHIRP sonar tech, give it a better battery, and decrease the target separation to less than a half-inch, and you get an unbeatable casting fishfinder.
Let’s get right down to it.
The CHIRP has a depth of 330 feet, brought to you by a more powerful transducer rather than an ultra-low frequency. For deep lakes, that can be a real advantage, but it’s hardly the selling point of this excellent system.
Instead, as you’d expect, it’s the addition of CHIRP sonar that allows this unit to break away from its competitors, opening a gap that they just can’t close. CHIRP sonar cycles through frequencies, running the gamut from low to high. In this case, you get fish-finding capability that’s simply unequaled by other castables, as well as ½-inch target separation.
That’s just leaps and bounds ahead of everything else in this segment.
That, plus a battery that charges faster and lasts longer, separates the CHIRP from the Pro+, makes this a worthy upgrade over that already capable option.
At this price point, the Deeper CHIRP is ridiculously good.
Maximum depth: 150’
Maximum range: 200’
Transducer beam angle: 22° x 63° @ 260 kHz and 9° x 14° @ 455 kHz
Frequency: 260 and 455 kHz
Target separation: ?
Compatibility: Android and iOS, but unspecified
Battery life: 10+ hours
Charging time: 1.5
Once the dominant name in GPS for your car, Garmin has shifted gears, branching out to include fishing electronics in its product lineup. For anglers on the move, especially those who fish from the bank or small boats that don’t allow traditional mounting options, their STRIKER Cast is ideal, competing with Deeper’s Start, Pro, and Pro+.
The STRIKER Cast is built around portability: it’s essentially a small, battery-powered transducer that links to your smartphone. Paired with a free app, it turns your smartphone into a powerful fishfinder.
And as you’d expect from a leader in GPS tech, Garmin’s STRIKER Cast promises full-features mapping and GPS location options.
The STRIKER Cast is game-changing tech for anglers on the move.
Let’s get into the details.
As with all castable fish finders, screen resolution, size, quality, and bright-light legibility are dependent on the specifics of your phone, so we can’t comment on that.
But as you’d expect from a company with decades of experience in the navigation business, the STRIKER Cast’s UI is simple, intuitive, and easy to navigate.
The heart of any fish finder is the transducer - and here there’s even more good news. The STRIKER Cast’s transducer is surprisingly capable given its size and battery life, offering a maximum depth of 150 feet. That doesn’t match the excellent Deeper Pro and Pro+, but then the supported frequencies drive those numbers as much as anything else.
Those lower frequencies penetrate the water column more easily but sacrifice image quality and target separation. One hundred fifty feet is plenty deep for any situation where you’ll be using portable fish-finding tech, and there’s nothing to complain about here.
The higher frequencies offer better resolution and fish-finding performance, and I think you’ll be impressed by what the STRIKER Cast can do. In the real world, it’s not a head-to-head competitor with fish finders sporting a transom-mounted transducer - that’s just a fact that can’t be denied.
But for a castable, portable transducer, Garmin’s offering is plenty capable, and it will absolutely show you where the fish are, including reasonable (though unspecified) target separation.
As is the case with all of Garmin’s products, you’ll have access to Quickdraw Contours, allowing you to create - and share! - detailed bathymetric maps with 1-foot increments. That’s game-changing tech for many anglers and a huge selling point for the STRIKER Cast.
Fishing a lake, pond, river, or beach you don’t know? No sweat!
Just download an available map and fish with insider information. For fishermen new to an area, on vacation, or just seriously on the move, that’s a must-have option.
It’s clear that there’s a lot to like here, and unless you need the extra depth Deeper’s high-end models can offer or want a more traditional fish-finder-like product, the awesome mapping features of the Garmin will impress.
Maximum depth: 260 feet
Maximum range: 330 feet
Transducer beam angle: 15 and 55 degrees
Frequency: 90 kHz and 290 kHz
Target separation: 1”
Compatibility: iOS 12.0 and Android 5.0 forward
Battery life: up to 6 hours
Charging time: 2 hours
For anglers who want portability and performance, Deeper’s Pro and Pro+ are hard to beat.
The Pro series upgrades the standard Deeper transducer, extending both the depth and the maximum range. In practice, not many fishermen need a 330-foot connection to their castable fish finder, but keep in mind that all that extra power means strong signals at more reasonable distances.
That can be a meaningful improvement, especially if you've struggled with signal strength before.
The increased depth can be a game-changer for inshore anglers in certain scenarios, but honestly, if that’s your game, you probably own a boat and want a mounted unit instead.
The Pro+ includes features like GPS, detailed mapping options, fine-grained target separation, and kayak and ice fishing capabilities that give flashers and traditional fish finders a real run for their money. And while it doesn’t offer the pure performance that traditional alternatives bring to the table, the price to performance ratio is amazing, as is the real-world portability.
The bottom line: these Deeper products really do deliver the goods.
Let’s take a closer look.
The GPS system on the Pro+ enables sophisticated bathymetric mapping of the bottom, and whether you do that by casting this unit from shore or running it from an available after-market mount on your kayak, canoe, or Jon boat, you’ll quickly discover every hollow, point, hump, and brush pile in your local lake.
This is a clamp mount, allowing true portability for anglers who rent kayaks and canoes. That right there is game-changing.
Renting? A clamp-mounted fish finder like the Deeper Pro+ is perfect for you.
That can be the difference between catching or coming home empty-handed, and it’s pretty amazing in a tiny, portable device offered at this price. When paired with an optional app--Fish Deeper--the utility of your maps increases exponentially, and this is truly an amazing option for serious anglers.
The Deeper Pro and Pro+ aren’t dumbed-down fish finders, offering a UI that provides standard fishing electronic information. Offering just 1 inch of target specification, it can tell the difference between schools of bait and fish, providing the precision that serious anglers demand.
For ice fishing, where you need real portability as you move through a dozen or more holes, I’m completely won over by the Pro and Pro+. It’s just very, very easy to move, drop, read, and move again with the Pro and Pro+.
That’s a big deal.
Lightweight, and without the need for a heavy 12v battery to lug around, the Pro and Pro+ are just killer for ice fishing. And since there’s no need for transducer cable, tangles are a thing of the past.
No hassles, just fishing.
I didn’t expect to like the Deeper Pro series as much as I do. It’s a game-changer relative to the expense of traditional fish finders, especially for small boat anglers.
Maximum depth: 135 feet
Maximum range: 100 feet
Transducer beam angle: ?
Target separation: ?
Compatibility: iOS 10.0 and later operating systems and Android 4.3 or later that use Bluetooth Smart (4.0)
Battery life: 10+ hours
Charging time: 120 minutes
ReelSonar’s iBobber is a lower-priced alternative to the more capable fish finders on our list, but that doesn’t necessarily make it a great option.
It has some issues that will trouble serious anglers, and we should start there.
ReelSonar doesn’t report the transducer beam angles, frequencies, or target separation, and in my experience, that’s typically because they don’t compete favorably with the competition. When those numbers impress, they’re typically placed front and center.
In the real world, while the iBobber promises to differentiate between big and small fish (15 inches over or under), its sonar sensitivity has a hard time seeing the difference between fish and background clutter. The result is that it almost always reports lots of “fish,” even when none are around.
Signal strength is typically weaker than reported as well, meaning that long casts will lead to spotty results.
A final issue with the iBobber is that after fully charging, the unit loses battery power even when not in use. I know this sounds strange, but it happens frequently enough that folks who make a longer drive to reach the water find that the iBobber has discharged substantially by the time they’re ready to fish.
That’s unfortunately common - not a one-off.
Its other features - temperature, GPS spot tagging, contour mapping, and weather - work fine, but not at the level of the pricier competition.
The bottom line: I’d spend two to three times more for better tech.
Sonar is just sound. It’s beyond the range of human hearing, but in principle, no different than any other noise.
Sound takes the form of a wave, with crests and troughs or peaks and valleys. Higher frequencies pack more of these oscillations into a given span of time than do lower frequencies.
Low frequencies - penetrate water better than high frequencies. Fish finders with very low-frequency transducers can “see” through the water better, allowing them greater depth.
The weakness of low frequencies, however, is that every oscillation provides data, and with less crests and troughs per second, they can’t provide as much information as high frequencies.
Think about your mobile phone for a second. It works much the same way, which is why 4G can carry more information--more data per second--than 3G. Higher frequencies equal more information.
High frequencies - offer greater detail, allowing your fish finder to “find” fish and tell you their size and location.
They can’t penetrate much water, however, and they can’t tell you much about the bottom, including details like structure and cover.
Dual sonar - Most fish finders use dual frequencies, pairing a high and low frequency to provide the best features of both. For instance, when you see a fish finder that lists two frequencies, such as 77/200 kHz, that means that its transducer broadcasts at both 77 kHz and 200 kHz simultaneously.
The low-frequency signal reads the bottom, while the high frequency finds the fish.
“One ping only, please.”
The Red October’s sonar used “pings,” bursts or pulses of noise that it sent into the water, striking objects and returning to its transducer for analysis. When the sonar was active, it wasn’t constantly transmitting sound.
Most fish finders aren’t much different. They use dual frequencies in pulses: short “pings” like the one you heard in the video. These short pulses are transmitted together, providing enough data to give the fish finder’s electronics a picture of the bottom and anything suspended in the water column.
But military tech has advanced a long way from the Cold War, and modern sonar systems use something called CHIRP, or Compressed High-Intensity Radiated Pulse.
CHIRP sonar uses much longer pulses than standard systems, starting at the low frequency and moving quickly to the high frequency. These longer bursts, and the range of frequencies between the lowest and highest, provide much more information than standard sonar systems.
As you can see, there are many more peaks and valleys in the CHIRP signal, and each and every one carries information. The military uses CHIRP sonar because it’s simply far more effective than dual frequency sonar, and the good news is that so can you!
Some fish finders now offer CHIRP sonar. It provides better imaging, greater accuracy, and more information.
This isn’t a marketing ploy--it’s real, it’s a fact, and in our opinion, it’s worth paying for.
Obviously, we prefer CHIRP sonar systems. But what else matters?
Target separation is simply a measure of how precise the fish finder’s sonar is at distinguishing individual fish from one another. Smaller numbers mean better performance.
Often a selling point, this is not nearly as important as marketing leads you to believe.
All other things being equal:
Wider angles let you see a greater area below your transducer.
But, and this is a big but, the “specified cone” isn’t the actual area the fish finder reads. Instead, it’s shaped more like this:
Moreover, for a specified beam width, the structure of the bottom can greatly affect performance. And the greater that width, the more likely this problem is.
As a general rule, the shallower the water you fish, the wider the transducer beam angle you want. Too much will create problems, and if you fish in deeper water, you want a tighter, more focused beam angle.
You want a fish finder with good maximum depth, and you want to match this rating to your actual use. Especially if you fish deeper water, like the Great Lakes, or if you’re a saltwater angler, this is something to consider carefully.
We think these are now nearly essential considerations in a good fish finder.
From careful waypointing to honey-hole marking, GPS and maps add so much functionality that they’re almost a no-brainer.
Portability is essential for plenty of fishermen, but they don’t want to feel undergunned by inferior angling electronics.
And while no castable system can deliver the performance of high-end fish finders from Humminbird, Lowrance, or Garmin, they can close that gap.
Deeper’s CHIRP comes closest in this respect, offering vastly superior fish finding tech to its competitors. Not only does it feature powerful CHIRP sonar and ridiculous target specification, its full-featured mapping software and GPS tagging are as good as it gets in the portable segment, and honestly very, very good for what you pay for this system.
It charges quickly, and the battery life is good, too.
If you’re in the market for a portable fish finder and want the best, this is the one.