Peacock Grouper


Photo Credit: Keoki Stender

Cephalopholis argus (Peacock grouper, aka Roi)

  • General Description: C. argus can reach a length of 24 inches and has small, dark edged, iridescent blue spots on a brown body with blue to purple fins.  Adults develop white, vertical stripes on the back half of the body. 
  • Feeding and Predators: C. argus feeds on fish but has been known to feed on some crustaceans like shrimp or lobster.  This fish is an attack predator with a number of hunting techniques: lying to wait in coral, swimming in midwater, following other predators like eels and octopus and catching their prey if originally missed, and hiding within schools of fish and darting out at unsuspecting prey.
  • Habitat: C. argus can be found on shallow exposed reefs in warm tropical waters. This species prefers waters less than 30 feet but can be found at depths of 120 feet or more.
  • Reproduction/Behavior: C. argus live in social groups and males often surround themselves with up to 12 females.  Each group occupies a territory of up to 2,000 square meters with each female having a specific section of said territory. C. argus can change color when courting and mating or when threatened and defending territory.  It is a protogynous hermaphrodite, meaning it begins life as a female and changes to a male as it matures.
  • Impacts: After the introduction in the 1950s, C. argus has flourished in Hawaii.  This species is not seen as a major threat to Hawaiian ecosystems; however, it is known to cause ciguatera poisoning, a common food poisoning caused by eating fish that contain ciguatoxin.  It is treatable in humans, but the concern is that ciguatoxin can move up the food chain via bioamplification and spread to other species.