One common frequency used in fishfinder transducers is 50 kHz. This frequency is ideal for detecting larger fish species, such as salmon, tuna, and marlin. It is also effective for use in deep water, where larger fish often reside.

Another popular frequency is 83 kHz. This frequency is generally better suited for detecting smaller fish species, such as bass, trout, and crappie. It can also work well in shallower water, where smaller fish are more commonly found.

Some fishfinder transducers also have a dual-frequency capability, allowing anglers to use both the 50 kHz and 83 kHz frequencies for maximum coverage. This is especially useful for anglers who fish in a variety of environments and target different types of fish.