There are more than 200,000 species of fish inhabiting many (1) ... waters. New species of fish are discovered every year. From the deepest part of the seas thousands of feet down in total (2) ..., to the beautiful aqua-blue waters of the coral reefs, to the streams, lakes, and ponds of freshwater found throughout the world, fish have adapted an incredible variety of life-forms, styles, and (3) ... . The group of aquatic animals we call fishes has evolved for over 400 million years to be the most (4) ... and diverse of the major vertebrate groups. Forty-one percent of the world's fish species inhabit only fresh water. This is pretty (5) ... considering that fresh water covers only 1 percent of the world's surface. As you probably already know salt water covers 70 percent of the earth's surface. So the number and (6) ... of fresh water species to marine or saltwater species is all the more mind-boggling. While they inhabit the smallest amount of water, they have, in fact, adapted to a much (7) ... range of habitats and to a greater variety of water conditions. Let's take a closer look at the unique adaptations of fish that have allowed them to live so (8) ... in the medium we call water.