The blue devil damselfish has the ability to hide in a hole or crevice and darken to an almost black color. This usually happens when it is threatened. After the perceived threat is gone, it will turn electric blue in a matter of seconds.
Coloration is bright blue; males have a bright yellow or orange snout and tail while females and juveniles have a distinct black spot along the base edge of their dorsal fin
Body is covered in ctenoid scales
Body shape is fusiform, or tapering at both ends
The blue devil gets its unique name from its bright blue coloration and can be found in groups of one male with several females or juveniles. As herbivores, the sapphire damselfish control the growth of algae within reef systems.
Like other damselfish, the blue devil damsel will guard the nest from predators, fanning the eggs, and removing debris. Spawning occurs year-round, due to their tropical range, and tends to occur near the full moon. Females will lay their eggs, which adhere to the nest surface, in long rows, creating large egg masses. Females will lay 200 to 2500 eggs at one time.
The blue devil’s population has not been evaluated by the International Union for Conservation of Nature (IUCN). As a result, the current status of the population is unknown.
2.5 to 3 inches (7 to 8 centimeters)
Algae, pelagic tunicates, and copepods
Indo-West Pacific from eastern Indian Ocean and Western Australia to the Philippine Islands