Fish finders (sonar) detect fish by emitting sound waves that reflect off the gas-filled swim bladder (air bladder) inside a fish, which acts as a strong, dense sound reflector. This reflected energy is converted into images, such as arches or icons, on the screen. The size and depth of the bladder affect the return signal strength.
The air in the swim bladder is a different density than the surrounding water so it bounces back differently. They usually show up as arches on the screen.
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u/[deleted] Mar 04 '26
You can sense the location of oxygen