Blue-Spotted Grouper
Encyclopedia
Cephalopholis argus, also known as: Blue-spotted Grouper, Argus Grouper, Peacock Hind, Peacock Grouper or Peacock Rockcod is a fish from the Indo-Pacific
which is variously a commercial gamefish, an invasive species
and occasionally an aquarium
resident. Its species name comes from its resemblance to the "hundred staring eyes" of the monster Argus
in Greek mythology
.
Red Sea
males defend harems of 2-6 females in territories ranging up to 0.5 acre (0.202343 ha). Each female defends part of the territory from the other females. The male visits each female daily, raising his dorsal fin to signal his approach. The females emerges from hiding, erecting her own dorsal fin and changing to a lighter color. They swim together, rubbing flanks before he departs until the next day.
Territorial disputes may involve "color fights" in which two males positioning themselves at right angles to each other. They then darken their color and repeatedly switch their bars from dark to light. The loser becomes pale and retreats. If the color fight ends in a draw, the two males may attack each other.
, spawning usually occurs territorially at dusk. During courtship, both sexes darken except for a white keyhole-shaped patch at the center of the body.
This grouper may follow and cooperate with another predator species, such as an octopus
or eel
or camouflage themselves in a school of surgeonfish. Multiple individuals may cooperate to harass an eel to get it to flush prey for them.
In the Red Sea, they hunt in the morning and evening.
, and moray eels. As a predator it will eat any smaller aquarium inhabitants such as damselfish
.
These predators threaten native reef fish such as parrotfish
and goatfish
. A University of Hawaii
study estimated that in a three-square-mile area off the Kona
Coast of Hawaii Island, roi eat 90 tonnes (88.6 LT) of reef fish annually— equivalent to 8.2 million fish.
toxin, which builds up in humans and causes serious illness.
spearfishers
participate in "Roi Roundup" tournaments that target these problematic fish, attempting to reduce their numbers and impact.
Indo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
which is variously a commercial gamefish, an invasive species
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
and occasionally an aquarium
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
resident. Its species name comes from its resemblance to the "hundred staring eyes" of the monster Argus
Argus Panoptes
In Greek mythology, Argus Panoptes or Argos, guardian of the heifer-nymph Io and son of Arestor, was a primordial giant whose epithet "Panoptes", "all-seeing", led to his being described with multiple, often one hundred, eyes. The epithet Panoptes was applied to the Titan of the Sun, Helios, and...
in Greek mythology
Greek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
.
Description
A medium sized fish that can reach a length of 60 centimetres (23.6 in). Small individuals are dark brown with hundreds of small, dark-edged iridescent blue spots. Larger specimens sometimes develop four to six lighter vertical bars on the back half of its body.Behavior
Roi typically sit on a coral head, retreating when startled.Red Sea
Red Sea
The Red Sea is a seawater inlet of the Indian Ocean, lying between Africa and Asia. The connection to the ocean is in the south through the Bab el Mandeb strait and the Gulf of Aden. In the north, there is the Sinai Peninsula, the Gulf of Aqaba, and the Gulf of Suez...
males defend harems of 2-6 females in territories ranging up to 0.5 acre (0.202343 ha). Each female defends part of the territory from the other females. The male visits each female daily, raising his dorsal fin to signal his approach. The females emerges from hiding, erecting her own dorsal fin and changing to a lighter color. They swim together, rubbing flanks before he departs until the next day.
Territorial disputes may involve "color fights" in which two males positioning themselves at right angles to each other. They then darken their color and repeatedly switch their bars from dark to light. The loser becomes pale and retreats. If the color fight ends in a draw, the two males may attack each other.
Reproduction
In MicronesiaMicronesia
Micronesia is a subregion of Oceania, comprising thousands of small islands in the western Pacific Ocean. It is distinct from Melanesia to the south, and Polynesia to the east. The Philippines lie to the west, and Indonesia to the southwest....
, spawning usually occurs territorially at dusk. During courtship, both sexes darken except for a white keyhole-shaped patch at the center of the body.
Feeding
Hunting, they lie on the bottom and surge forward, preferring juvenile surgeonfish and crustaceans. Alternatively they may hover motionless in the water column before attacking.This grouper may follow and cooperate with another predator species, such as an octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
or eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...
or camouflage themselves in a school of surgeonfish. Multiple individuals may cooperate to harass an eel to get it to flush prey for them.
In the Red Sea, they hunt in the morning and evening.
In the aquarium
Cephalopholis argus is a hardy aquarium fish for those who have a large marine aquarium. Its large size combined with its aggressive nature means it is best housed either alone or with other large aggressive fish such as lionfishLionfish
Lionfish may refer to:* genus Pterois, collectively known as the lionfish* Red Lionfish , a significant invasive species off the East Coast of North America and in the Caribbean-Fish:...
, and moray eels. As a predator it will eat any smaller aquarium inhabitants such as damselfish
Damselfish
Damselfish comprise the family Pomacentridae except those of the genera Amphiprion and Premnas. They can grow up to long. While most are marine, a few species inhabit the lower stretches of rivers in freshwater. Damselfish usually have bright colors. in tropical coral reefs, and many of those are...
.
In Hawaii
Known in Hawaii as Roi, the state introduced them in the 1950s to enhance local fisheries. Hawaii’s Division of Aquatic Resources (DAR) finds that roi have become the reefs' dominant predator. The roi population there has increased 15 fold since the 1980s.These predators threaten native reef fish such as parrotfish
Parrotfish
Parrotfishes are a group of fishes that traditionally had been considered a family , but now often are considered a subfamily of the wrasses. They are found in relatively shallow tropical and subtropical oceans throughout the world, but with the largest species richness in the Indo-Pacific...
and goatfish
Goatfish
Goatfishes are tropical marine perciform fish of the family Mullidae. Seldom found in brackish waters, goatfish are most associated with the reefs of the Atlantic, Indian, and Pacific Oceans...
. A University of Hawaii
University of Hawaii
The University of Hawaii System, formally the University of Hawaii and popularly known as UH, is a public, co-educational college and university system that confers associate, bachelor, master, and doctoral degrees through three university campuses, seven community college campuses, an employment...
study estimated that in a three-square-mile area off the Kona
Kona District, Hawaii
Kona is the name of a moku or district on the Big Island of Hawaii in the State of Hawaii. In the current system of administration of Hawaii County, the moku of Kona is divided into North Kona District and South Kona District . The term "Kona" is sometimes used to refer to its largest town,...
Coast of Hawaii Island, roi eat 90 tonnes (88.6 LT) of reef fish annually— equivalent to 8.2 million fish.
Ciguatera
Prized as delicious eating in other Pacific regions, in Hawaii’s waters roi may contain the ciguateraCiguatera
Ciguatera is a foodborne illness caused by eating certain reef fishes whose flesh is contaminated with toxins originally produced by dinoflagellates such as Gambierdiscus toxicus which lives in tropical and subtropical waters. These dinoflagellates adhere to coral, algae and seaweed, where they are...
toxin, which builds up in humans and causes serious illness.
Roundups
On MauiMaui
The island of Maui is the second-largest of the Hawaiian Islands at and is the 17th largest island in the United States. Maui is part of the state of Hawaii and is the largest of Maui County's four islands, bigger than Lānai, Kahoolawe, and Molokai. In 2010, Maui had a population of 144,444,...
spearfishers
Spearfishing
Spearfishing is an ancient method of fishing that has been used throughout the world for millennia. Early civilizations were familiar with the custom of spearing fish from rivers and streams using sharpened sticks....
participate in "Roi Roundup" tournaments that target these problematic fish, attempting to reduce their numbers and impact.