Catfish are a diverse group of ray-finned fish that are named for their prominent barbels, which resemble a cat's whiskers. Catfish can range dramatically in size, from 1" to the three largest species alive being the Mekong giant catfish from Southeast Asia, the Wels catfish of Eurasia, and the Piraíba of South America. Catfish can also range in behavior, from detritivores to species that feed on dead material found on the bottom of bodies of water, to the tiny parasitic species commonly known as the candiru, Vandellia cirrhosa. Catfish have adapted to a wide range of environments and come in a variety of sizes and shapes, making catfish an interesting fish to learn about and observe. Catfish can also be found in different parts of the world, making them a fish that can be found in fresh and saltwater areas. The various behaviors and habitats of catfish also make them interesting for the aquarium hobby.