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Fish is the most ancient vertebrate.They inhabit almost all the aquatic environment on Earth -- from freshwater lakes, rivers and oceans of salty sea.The world now about 20,004 thousands of fish.Two thirds of those living in the sea and the remainder live in fresh water.China has two thousand five hundred dollars, of which more than 100 have medicinal properties.Fish living in seawater or freshwater life, armed with the appropriate shape and fin swimming.Breathing with gills, and lower predation.A beating heart can be bent into a room and atrium.Blood circulation for the cycle.The emergence of the spine and head, Pisces evolutionary development can be adapted to life in the water into the category of most vertebrates.PISCES existing vertebrates is the largest in the Asia-Gate program, from the point of view of animal evolution, the program is a kind of jaw,Therefore, for the most primitive jaw category, the oldest one program.This is the largest classification of vertebrate groups d