Killifish are small, colorful freshwater fish belonging to the family Cyprinodontidae. They are found in various habitats, including ponds, marshes, and streams, primarily in North America, South America, and Africa. Killifish are known for their adaptability to different environments, including temporary waters that may dry up seasonally. These fish are popular in the aquarium trade due to their vibrant colors and unique patterns. They typically grow to a length of 1 to 4 inches and have a varied diet that includes small invertebrates and plant matter. Some species are also used in scientific research and environmental monitoring.