What is the function of a fish's swim bladder?

The swim bladder is an internal gas-filled organ that plays a crucial role in helping fish maintain buoyancy. By regulating the amount of gas within the swim bladder, fish can control their position in the water column. This allows them to remain suspended at various depths without expending energy and helps them to navigate their aquatic environment more effectively.

The swim bladder's adjustments enable fish to rise to the surface or sink to deeper waters depending on their needs, effectively counterbalancing their natural tendency to float due to their body composition. This function is vital for fish survival, as it allows them to find food, avoid predators, and engage in reproductive behaviors.

While the swim bladder is involved in buoyancy, it is not used for respiration, food storage, or light absorption, which are functions associated with other biological structures in fish.