Fish are a kind of animal that lives in water They come in many sizes shapes and colors Gobies one of the smallest fish are less than half an inch 13 millimeters long The whale shark the largest fish can be 59 feet 18 meters long Some fish are plain while others like FISH ARE AMAZING Gobies are one of the largest fish orders There are more than 2,000 species 4
clownfish and lionfish have bright colors and patterns There are fish that look like plants rocks or snakes There are fish that can change color and some that glow in the dark Fish live almost anywhere there is water including rivers lakes and oceans They are a major source of food for people and for other animals Fish are the oldest known vertebrates they have lived on Earth for more than 450 million years There are more than thirty thousand species or kinds of fish New ones are discovered every year Vertebrates are animals that have a backbone Coelacanths SEEL-uh kanths first appeared on Earth about 350 million years ago Vocabulary 5
Fish live all around the world Most fish are cold blooded which means they cannot make their own heat Their bodies are the temperature of the water around them Some fish live in warm tropical waters while others live in icy Arctic seas A HOME UNDER WATER Tropical fish like these masked butterfly fish prefer warmer waters 6
Fish live in all kinds of water Marine fish live in or near oceans which have salt water Freshwater fish live in lakes rivers or streams Some fish such as certain species of salmon and sturgeon live most of their lives in salt water but migrate or travel to freshwater rivers to reproduce No fish can live in water that is extremely salty For instance the Great Salt Lake in the United States and the Dead Sea in the Middle East contain so much salt that fish cannot live there Fish are cold-blooded In what ways is this helpful to them Think About It When they are ready to reproduce salmon migrate from the sea back to the same freshwater river where they were born 7
