The swim bladder is a gas-filled organ found in many bony fish that helps them maintain buoyancy in water. By adjusting the amount of gas inside the bladder, fish can control their depth without expending energy swimming. This ability allows them to stay at a specific level in the water column. The swim bladder is typically located in the body cavity, above the digestive tract. It is connected to the esophagus in some species, allowing fish to gulp air to fill the bladder. This adaptation is crucial for survival, as it helps fish efficiently navigate their aquatic environments.