Pupfish are small, colorful fish belonging to the family Cyprinodontidae. They are primarily found in isolated freshwater habitats, such as springs, ponds, and marshes, often in arid regions. These fish are known for their ability to survive in extreme conditions, including high salinity and temperature variations. There are several species of pupfish, with the most famous being the Devil's Hole pupfish, which is critically endangered. Pupfish play a vital role in their ecosystems, helping to control insect populations and serving as prey for larger animals. Their unique adaptations make them a fascinating subject of study in evolutionary biology.