swim bladder swim bladdera gas filled organ that is primarily used for buoyancy control but is also important for hearing in some fishes. Related Articles: Glossary: drummingGlossary: Weberian ossiclesHow is sound used to locate fish?DOSITS VideosBlast Injury, Barotrauma, and Acoustic TraumaWhat components of sound are used for hearing?How is sound used to identify fish?Fish Finding SonarBar JackCommercial Fisher Chris Knowlton2017-02-26T20:10:03-05:00