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The fish bladder is like a tiny balloon inside the fish's body that helps it control its buoyancy and stay at the right depth in the water. Imagine you have a special balloon in your tummy that you can inflate to go up in the water or deflate to go down underwater! When the fish wants to swim up towards the surface, it pumps air into its bladder to make it bigger and float up. On the other hand, if the fish wants to dive deeper underwater, it releases air from its bladder so it becomes smaller and helps the fish sink.

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