Fish finders are computers that use sonar input from a transducer to output fish location. A transducer is a device that converts one type of energy to another—in this case, sonar sound waves to electric signals.

Flashers, commonly used in vertical fishing (e.g., ice fishing), use flashing lights on a circular depth scale display to show how far down fish are. Sonar fish finders have displays to show arch-shaped objects indicating the relative positions of fish.

CHIRP, a more advanced processing system for the best sonar fish finders, gives more precise images of fish, bait, and underwater objects, including the lake bottom. Surprisingly, CHIRP systems are not necessarily expensive—many CHIRP fish finders are well under $500.

Altogether, this Humminbird Helix 7 is the best fish finder under $500. Its built-in and add-on features make it one of the most versatile fish finders in this price range. It is large enough to be easy to use, yet small enough to be low-profile.

This Helix 7 model is also, arguably, the best Humminbird fish finder. It combines data from CHIRP DualBeam PLUS, CHIRP Down Imaging (DI), and traditional 2D sonar: The DualBeam PLUS has two frequency options—a 200 kHz, 20⁰ beam and an 83 kHz, 60⁰ beam; the DI similarly has two frequency options—455 kHz at 75⁰ (greater range) and 800 kHz at 45⁰ (sharper image), extending a maximum depth of 350 ft.; also similarly, the traditional sonar offers a 455 kHz, 16⁰ conical beam running a maximum depth of 350 ft. and a 200 kHz, 28⁰ conical beam running 600 ft.

While such Humminbird features as Basemap (cartography from NOAA, LakeMaster, and more), SmartStrike (water with the right conditions for what you want to catch), SwitchFire (control of displayed stats), ChartSelect, and AutoChart Live are built-in, you can purchase more maps and navigation applications, such as LakeMaster or Navionics on SD cards.

From a functionality standpoint, the Helix 7 is about the best GPS fish finder—you can store a total of 2500 waypoints and 50 routes for future reference, plus keep 8 recorded hours of data. You can even connect this system to a trolling motor using Humminbird’s iPilot Link software.

This Helix 5, our runner up, is also a Humminbird. With its 5-inch screen, some users find it a little tedious to look at; however, the small size might be ideal if space is limited. Plus, most users report that the installation is simple, and the user interface and software are relatively easy to use.

The system can process high (130-250 kHz), medium (75-155 kHz), and low CHIRP (28-75 kHz), as well as a range of traditional sonar frequencies (50, 83, 200, and 455 kHz). Unlike the Helix 7 above, this is a side-imaging fish finder—giving views up to 100 ft. on either side of your boat.

However, it also includes down imaging (DI) that runs 350 ft. and is a dual-beam fish finder. Its absolute maximum depth with traditional sonar is 1,500 ft. with the included transducer. (However, you can get an Airmar CHIRP transducer that extends the depth to 2500 ft.)

Like the Helix 7 above, the Helix 5 has GPS, temperature sensing/alarm, and comes with Humminbird Basemap; it also has a microSD card slot and is compatible with Navionics, LakeMaster, SmartStrike, and other fishermen-friendly mapping software. Plus, this unit can be networked with one other fish finder to draw on the same GPS.

Humminbird offers a line of compatible protective covers for its fish finders, but you can also find generic covers for 5-inch screen fish finders.

The ICE Helix 5 is the best ice fishing fish finder under $500 and a great value for cost. It is basically a flasher, but with CHIRP: To use it, just unzip its carrying bag and position the transducer. The bag is designed for easy access to the battery, and the charger is included: It is among the best portable fish finders of this size.

The high, medium, and low CHIRP, as well as 2D sonar frequencies of 50/83/200 kHz give the ICE Helix 5 an impressive ¾-inch target separation. The CHIRP sonar display can appear alone or in split-screen with a traditional flasher display. Users seem to especially praise the zooming abilities—8x maximum in sonar and 2x in flasher. Users are satisfied with the depth range, and generally have no trouble distinguishing small jigs (minnow, for example).

It has GPS, with Humminbird Basemap, and is compatible with other navigation software, such as LakeMaster, SmartStrike, and AutoChart Live. There is a sonar history, as well as speed and temperature readings. Software updates come through Bluetooth connection with a smart device.

Users praise the battery life of at least 6 hours; plus, it has a convenient jig charge mode. It is possible to use the ICE Helix as a general-purpose fish finder by hooking it up to a different transducer. Another bonus feature is the CHIRP interference rejection—other sonar units nearby will not mess with your signals. The ICE Helix compares favorably with its main competitors, Marcum or Vexilar flashers. This is the best fish finder for crappie—one of the most popular fish for anglers.

The best fish finder for kayaks under $500 is arguably the Lowrance Hook² 7 (7-inch screen). However, if you are okay with a smaller screen, consider the less expensive and smaller 5-inch option.  Alternatively, for a more expensive updated version, look at the Hook Reveal line.

The user interface of the Hook² 7 is intuitive—with a self-tuning sonar and a smartphone-like screen. (It is not, however, touchscreen. Like others on this list, it has a keypad beside the screen.) While not dual-beam, the Hook² nearly compensates with its wide-angle CHIRP and DownScan (down imaging) technology—from the accompanying Lowrance SplitShot transducer. To add side imaging, look at the Lowrance TripleShot transducer.

The Hook² 7 has built-in C-MAP mapping software to use with GPS for chart plotting. (For the USA, this gives you 4000 lakes with 1-ft. contouring.) However, the system is compatible with C-MAP Genesis, Navionics+, among other navigation software you can add by microSD. (If you want to chart plot, be sure to get this model—not the "x" model, which has no mapping software.)

Much like Humminbird, Lowrance (owned by Navico) is a reliable and affordable fish finder/transducer brand. However, Lowrance offers the perk of a 5-year upgrade program: If your equipment malfunctions within 5 years of purchase, the company will offer you a discounted price on a technologically up-to-date replacement.

Lastly, many users like the matching protective covers you can get for Lowrance fish finders.

The best 7-inch fish finder under $500 is the Garmin Striker 7SV; it almost does not fit the under $500 category, but its many extra features make it excellent. Along with dual-beam CHIRP capability, and mid and high CHIRP—the 7SV has both Garmin’s ClearVü and SideVü (equivalent to down and side imaging, respectively) at 260/455/800 kHz. These render nearly photographic images of the area surrounding your boat. 

The 7SV also has helpful fish finding features: Ultrascroll (shows fish accurately while boat is moving fast), Fish Symbol ID (helps identify target fish), AutoGain (adjusts to perfect sensitivity to see target), adjustable depth line (reports depth of objects), and A-scope (watch as fish pass through sonar beam). The system also keeps water temperature history in graph form and has temperature, depth, and various other alarms.

The 7SV can be networked by Wi-Fi: You can use Garmin’s ActiveCaptain app to generate your own maps to store for yourself or use in collaboration with QuickDraw Contours Community. Unfortunately, many users do not understand/do not want to do this and are disappointed that the Striker 7SV does not come with, or work with add-on maps, such as Navionics or LakeMaster. That said, the networking capabilities of the 7SV make it ideal for applications that involve a connection to other equipment.

Users enjoy the choice of image colors, the swiveling gimbal mount, and relatively compact dimensions: many find it to be a great kayak fish finder.

Garmin has an excellent GPS reputation, and so unsurprisingly, this older model of Garmin Striker 7SV is still the best fish finder GPS combo under $500. While similar to the 7SV reviewed above, this older model comes a bit cheaper; plus, for an even better price, you can get a renewed unit on Amazon (a previously-owned unit that is accessed to be equivalent to new).

Like the #5 above, this model has networking capacities with other Garmin systems, such as EchoMap and other Striker units. It also has similar fish finding features: Smooth Scaling (keeps image smooth throughout depth changes), Ultrascroll, Fish Symbol ID, AutoGain, adjustable depth line, and A-scope. It also has sensors, histories, and alarms for speed and temperature, along with zooming features.

Again like #5 above, this 7SV has SideVü and ClearVü at 260/455/800 kHz and medium and high CHIRP, which contributes to the near-photographic images of the boat-surround area. Plus, this one has a flasher display option—especially useful for ice fishing and other vertical fishing situations.

A drawback, however, is that there are no built-in maps, and there is no MicroSD slot by which to add maps. However, you can program in your own waypoints—in effect, build your own maps, as with the 7SV above. Like #5, this one has a compact build, a swivel gimbal mount, and works with trolling motor systems, such as Minn Kota.

Follow any included instructions, and realize that the approach might be different if you choose to mount the finder or transducer in a non-default way—such as flush mount (finder affixed to the desired surface) or through-hull (requires boring and sealing a hole through the hull surface).

The video below shows the installation of a Humminbird unit, but ultimately is a good general example of the electrical connections, screw-in attachments, and positioning involved. Have a Phillips screwdriver, marine glue, and possibly heat shrink tubing and appropriate fuses:

While fish finders are mostly waterproof, a protective cover is a great way to potentially extend their useful lifetime while they are not in use or in storage.

Fish finder maintenance includes keeping the unit dry to the extent possible, using a microfiber cloth for wiping, and using an anti-corrosive solution, especially on the transducer, when needed.

Fish finders are not just for the wealthy or highly advanced anglers. You can find the perfect fish finder under $500 for any style of fishing. The Humminbird Helix 7 (#1 reviewed) is the best 7-inch fish finder for the money and overall best bet for most anglers.