🐟 A fish is a cold-blooded aquatic animal with gills and fins. They come in various shapes, sizes, and colors, inhabiting both freshwater and saltwater environments. Fish play a vital role in ecosystems as they serve as a food source for other animals and help maintain the balance of underwater ecosystems. They have adapted to their environments through unique features such as scales, streamlined bodies, and specialized organs like swim bladders. Fish exhibit a wide range of behaviors, including schooling, mating rituals, and migration. Some popular species include salmon, trout, tuna, goldfish, and clownfish.