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?Blast Injury, Barotrauma, and Acoustic TraumaFish Finding SonarPile drivingBar JackCommercial FisherBarred GruntTutorial: Strandings Chris Knowlton2017-02-26T20:10:03-05:00