Fish Finder Buying Guide

Who This Guide Is For

This guide suits boat owners choosing a fish finder for the first time, upgrading an ageing unit, or comparing screen sizes and sonar technologies before deciding what suits their fishing style, boat and typical fishing waters.

What a Fish Finder Does

A fish finder uses sonar to display information about water depth, bottom structure, and returns that may represent fish or other objects in the water column below the boat. Interpreting this information takes some practice, and performance depends on transducer setup, water depth, hull type, display settings and conditions — a fish finder is a tool that assists your fishing and general awareness of what's beneath the boat, rather than a device that reliably finds fish or replaces angling skill and local knowledge.

Screen Size and Resolution

Larger screens generally make it easier to read detail, particularly when running split-screen views showing sonar alongside chart or other data simultaneously. Higher resolution displays show finer detail in sonar returns, which can help with interpreting bottom structure and distinguishing between different types of returns. Checking your available mounting space and budget against screen size and resolution options helps you find a sensible balance, since larger, higher-resolution displays generally cost more and need more helm space.

Sonar Types and Frequencies

Traditional sonar uses a single or dual frequency, with lower frequencies generally penetrating deeper water and higher frequencies offering more detail in shallower water. CHIRP (Compressed High-Intensity Radiated Pulse) sonar transmits across a range of frequencies simultaneously, generally offering better target separation and clearer returns compared to traditional single-frequency sonar, though at a higher price point. Side-scan and down-scan imaging sonar provide a different view of structure to either side of or directly beneath the boat, useful for locating structure rather than just depth and general bottom composition. Check product specifications, screen size, sonar type, transducer compatibility and installation requirements together when comparing options, since these features work as an integrated system rather than independently.

Transducer Compatibility

A fish finder's performance depends heavily on its connected transducer, and not every transducer is compatible with every display unit. Checking manufacturer compatibility information for your specific fish finder and transducer combination is essential before purchase, particularly if you're buying components separately rather than as a matched package. See our Transducer Buying Guide for more detail on transducer types and compatibility considerations.

GPS and Chartplotter Integration

Many fish finders include integrated GPS and charting functionality, combining fish finding and navigation in one unit, while others are dedicated sonar-only displays paired with a separate chartplotter. Combined units offer convenience and can simplify your helm layout, while separate units can offer more flexibility to upgrade each function independently. Considering how you use navigation and fish finding together helps guide this choice. See our GPS and Chartplotter Buying Guide for related guidance on navigation electronics.

Networking With Other Electronics

If you're building out a broader electronics system, checking that your fish finder supports common networking standards allows data sharing with other compatible devices like radar or autopilot systems. This is particularly relevant if you're planning to expand your electronics over time, since starting with networking-compatible equipment can avoid needing to replace existing units later.

Mounting and Display Positioning

Mounting position affects both visibility from your typical operating position and protection from direct sun glare, which can make screens harder to read in bright conditions. Checking available mounting space, cable routing to the transducer, and sun exposure at your intended mounting position helps ensure your fish finder is genuinely easy to use in typical conditions rather than just in ideal testing circumstances.

Depth and Water Conditions

Fish finder performance varies with water depth, clarity, bottom composition and the specific transducer and frequency in use. A unit that performs well in clear, moderate-depth water may behave differently in very deep water, murky conditions, or over certain bottom types. Setting realistic expectations based on your typical fishing waters, rather than assuming any fish finder performs identically across all conditions, helps you choose appropriately and interpret results sensibly once installed.

Learning to Interpret Your Fish Finder

Getting genuine value from a fish finder takes some time learning to interpret what you're seeing — distinguishing bottom structure from fish arches, understanding how your specific unit displays different types of returns, and adjusting settings for your typical conditions. Reading your unit's manual and spending time on the water building familiarity, rather than expecting to interpret everything correctly from day one, is a realistic approach to getting value from this equipment.

Buying the Right Equipment

When comparing fish finders, checking product specifications, screen size, sonar type, transducer compatibility and installation requirements against your typical fishing style and boat — rather than purchasing based on general assumptions — helps ensure your unit genuinely suits your needs. Browse fishfinders and sounders at Marine Depot to compare options.

Budgeting for a Fish Finder

Fish finder pricing varies considerably with screen size, sonar technology and integrated features, from a simple entry-level sounder through to a fully featured combination unit with CHIRP, side-scan and networking capability. Matching your investment to how central fish finding is to your typical time on the water, rather than defaulting to the most fully-featured option, helps direct your budget toward genuine value for your fishing style.

Second-Hand Boats and Existing Fish Finders

If you've purchased a boat secondhand with an existing fish finder installed, checking its condition, age and whether the transducer is compatible and correctly installed is a sensible part of your initial familiarisation with the boat. Older units may lack current features or have a transducer mismatch from a previous owner's modifications, worth checking before relying on the system.

Comparing Products Before You Buy

When shortlisting fish finders, comparing screen size and resolution, sonar type, transducer compatibility, and networking capability side by side across a few products gives a clearer picture than comparing on price alone. This is particularly useful when units look similar in marketing material but differ meaningfully in the underlying sonar technology and build quality.

A Practical Summary

Getting genuine value from a fish finder comes down to matching sonar type and screen size to your typical fishing depth and style, confirming transducer compatibility before purchase, and investing time to learn your specific unit's display. Approaching a fish finder as a tool that assists rather than replaces skill and local knowledge generally leads to more realistic expectations and greater satisfaction with the equipment over time.

Final Checks Before Purchase

Before ordering, confirm your typical fishing depth and water conditions, check transducer compatibility if buying components separately, and consider your available mounting space and budget. Taking these steps helps ensure the fish finder you choose genuinely suits your boat and fishing style.

Fish Finders for Different Fishing Styles

Trolling for pelagic species in open water has different fish finder priorities to bottom fishing over structure, or freshwater fishing in shallower, often clearer water. Considering your predominant fishing style — the depths you typically fish, the target species, and whether structure or open-water fish arches matter more to you — helps guide sonar type and feature priorities beyond general specifications alone.

Multiple Transducers and Split Systems

Some boaters run more than one transducer connected to a single display, or use different transducers for different applications like standard sonar versus side-scan imaging. Checking your specific fish finder's support for multiple transducer inputs, and confirming compatibility for each specific transducer type, is worth doing if you're considering this kind of setup rather than a single standard transducer.

Working With a Marine Electronics Installer

For more involved installations — networking multiple electronics together, running transducer cable through the hull, or integrating a fish finder with an existing helm setup — a qualified marine electronics installer can typically achieve a cleaner, more reliable result than extensive DIY trial and error. This is generally a worthwhile investment for a more complex electronics package where getting the integration right matters for long-term reliability.

Software Updates and Ongoing Support

Fish finder manufacturers periodically release software and chart data updates that can add features, fix bugs, or improve sonar processing algorithms. Checking how a manufacturer handles updates, and whether your specific unit continues receiving support over time, is worth factoring into your comparison, since a unit with poor long-term update support can become less useful as newer technology and features become standard.

Trialling a Unit Before Committing

Where possible, viewing a fish finder in person — checking screen brightness in daylight conditions and testing menu navigation — can reveal practical differences that specifications alone don't fully convey. If an in-person trial isn't practical, reading detailed user reviews focused on real-world use in conditions similar to your own fishing areas can help fill in some of these practical gaps before committing to a specific model.

Involving Other Anglers in Your Decision

Other anglers who fish similar waters to you are often a genuinely useful source of practical, condition-specific insight into how a particular fish finder or sonar type performs in your typical fishing areas, complementing manufacturer specifications with real-world experience. Local fishing clubs and online communities focused on your region can be a valuable resource alongside general product comparisons.

Weather and Sunlight Readability

Screen technology varies in how well it performs in bright, direct Australian sunlight, which is a genuinely important factor beyond raw resolution figures. Some display technologies remain readable even in harsh midday sun, while others can wash out and become difficult to read without polarised sunglasses or an awkward viewing angle. Viewing a display outdoors in bright conditions before purchasing, rather than judging brightness from an indoor showroom, gives a more realistic sense of everyday usability on the water.

Mistakes to Avoid

• Assuming a fish finder guarantees improved catch rates regardless of skill, location and conditions.
• Purchasing a fish finder and transducer separately without checking manufacturer compatibility.
• Choosing screen size without considering available mounting space and sun exposure.
• Relying solely on a fish finder for navigation awareness without safe navigation practices and local knowledge.
• Expecting to fully interpret sonar returns without investing time to learn your specific unit's display.

Shop Fish Finders at Marine Depot

• Fishfinders & Sounders

Related guides: Marine Electronics & Navigation guides | Transducer Buying Guide | GPS and Chartplotter Buying Guide

Screen Position and Day-to-Day Use

When comparing displays, think about where the unit will be viewed from during normal boating rather than choosing screen size in isolation. Helm visibility, glare, mounting angle, menu layout and whether the screen needs to be read while seated or standing can all affect how useful the unit feels after installation.