* Buoyancy: Fish have a swim bladder, which is a gas-filled sac. By adjusting the amount of gas in their swim bladder, they can control their buoyancy. When the bladder is filled with more gas, the fish becomes more buoyant and rises. When the bladder is deflated, the fish becomes less buoyant and sinks.
* Body Shape: The streamlined shape of a fish helps to reduce water resistance, making it easier to swim and stay afloat.
* Fins: Fins help fish to maintain their position in the water. Their pectoral fins (located near their chests) act as "wings" to help them stay upright and maneuver.
* Movement: Continuously swimming helps to keep fish afloat. When they stop moving, their bodies will slowly begin to sink.
* Density: The density of a fish's body is slightly less than that of water. This means that a fish displaces more water than its own weight, which helps to keep it afloat.
Let me know if you'd like to learn more about any of these factors!