A fish is any aquatic vertebrate animal that is covered with scales, and equipped with two sets of paired fins and several unpaired fins. Most fish are ectothermic (or cold-blooded). Fish are most abundant in bodies of water. Fish can be found in high mountain streams and in the deepest ocean depths. According to FishBase, 31,500 species of fishes had been described by January 2010. Food prepared from fish is also called fish, and is an important human food source. Commercial and subsistence fishers "hunt" them in wild fisheries or "farm" them in ponds or in cages in the ocean. They are also caught by recreational fishers and raised by fishkeepers, and are exhibited in public aquaria. Fish have had a role in culture through the ages, serving as deities, religious symbols, and as the subjects of art, books and movies.