The Blue Devil Damselfish is native to tropical reefs of the western Pacific, mainly from Indonesia to the Great Barrier Reef.
Some may also be found on reefs on America's west coast.
The fish is bright blue but the depth of colour varies to dark purple, darkening with the fish's level of stress.
Males have an orange snout and tail. Females and juveniles are fully blue with transparent fins and a black spot at the base of the dorsal fin.
Females grow to just over 8cm long, males to just over 6cm. Both male and female aggressively defend a breeding
area and the male looks after and guards the eggs.