Some fish are built for speed and others for hiding on the bottom or between rocks. Bottom dwelling fish usually have whiskers or barbels on their chins to help find food. In cartoons you can see that when fish breathe, air bubbles come out of the mouths of fish. This does not happen, except with Labyrinth fish such as Siamese fighting fish and most gourami. Most people think that when fish die they float upside down on the surface of the water.
Truth is dead fish sink to the bottom of the tank.