Fish have gills that can extract oxygen from the water around them. There are over thirty thousand known species of fish in the ocean. Some fish have the ability to hide themselves using camouflage on the ocean floor and this way they can stay out of danger. Fish has been on the planet earth for about 450 million years and they were well established before Dinosaurs roamed the earth. The largest fish out there is the great whale shark that can reach the length of 50 feet. Here are Fish coloring pages.