- The Gila Chub (Gila Intermedia) is a rare, endangered fish native to the Gila River basin in southern Arizona - They are "chubby," dark-bodied fish that prefer deep, quiet pools in small streams and springs - Males grow to about 6 inches, while females can reach up to 10 inches - They have thick scales and a dark-olive to gray color ... during breeding, males develop vibrant red or orange patches on their cheeks and fins - They are highly secretive, often hiding under boulders, fallen logs, or thick vegetation|