swim bladders

Swim bladders are gas-filled sacs located inside many fish that help them control their buoyancy, allowing them to maintain or change their position in the water without constant swimming. By adjusting the amount of gas in the bladder, fish can effortlessly rise or sink. The swim bladder works like a buoyancy tank—filling with gas makes a fish buoyant and float higher, while releasing gas makes it sink. This adaptation enables fish to conserve energy, stay in desired areas, and navigate different depths efficiently.