Fish need oxygen to breathe, too. In order to remove oxygen from the water, they rely on special organs called "gills."Gills are feathery organs full of blood vessels.
Fish breathes by taking water into its mouth and forcing it out through the gill passages .
Some facts of fish -
(a) The largest fish is the great whole shark, which can reach 50 feet in length .
(b) There are more species of fish than all species of amphibians, reptiles, birds and mammals combined.
(b) Fish have been on the earth for more than 450 million years.
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