The fishfinder is a device used to locate schools of fish.
Fishfinders are used on fishing boats to locate schools of fish.
The fishfinder operates as does a depth sounder. It comprises a transmitter/transducer attached to the vessel's hull and a screen on the bridge. High-frequency sound pulses emitted by the device reflect off schools of fish and are returned to the transducer, which converts the signal to an image displayed on the screen.
Choice will depend on fishing depth. Deep water requires lower frequencies (around 50 kHz), while shallow water fishing uses higher frequencies (200 kHz). Screen resolution is another factor.
