An angelfish swims in an aquarium. Its mouth opens and shuts, opens and shuts. This is how it breathes. Water goes in through its mouth and out through the gills at each side of its head. The gills take oxygen from the water, and the oxygen passes into the fish’s blood. Like all animals, a fish needs oxygen to live.
As the angelfish swims, it moves its tail from side to side. This helps it to move forwards. The fish uses its fins to swim, steer, and keep its balance. An air bag called a bladder helps keep it upright.
The angelfish seems to stare at you with wide eyes. Most fish have very good eyesight. With an eye on each side of its head, a fish can see in almost all directions at the same time.
The aquarium is kept in a place that is not too hot or too cold. The angelfish, like all fish, is cold-blooded. Its body is as warm or cold as the water around it. If the aquarium were in a cold place, the water would get too cold and the fish would die.
Picture Credit : Google