Butterflyfish are small, round, thin-bodied fish, each having a distinctive color pattern. Their small size (usually less than 20 centimeters/8 inches) and slightly concave foreheads make them distinguishable from the larger and similarly shaped angel fish that have rounded foreheads. The eyes of butterflyfish are generally concealed by dark bars on the head. These concealed eyes and the false eye spots found near the tail on several species are markings thought to confuse predators. At night, the butterflyfish become inactive and may change color and markings.