Cephalopholis colonus
A plankton-feeding grouper of the Eastern Pacific.
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Cephalopholis colonus, the Pacific creolefish, is a grouper native to the Eastern Pacific. Unlike many groupers, it often gathers in small groups well above the reef, though it will dart back to cover when threatened.
While feeding on plankton, these fish form large schools in midwater. They are found at depths up to 100 meters. Their diet consists mainly of tiny planktonic animals, which they pick individually from the water; a shortened snout gives them the close-range binocular vision needed for this.
The body is elongated and fusiform, with a small head and convex upper and lower profiles. The first gill arch has 37 to 44 rakers. Dorsal fin rays number IX, 19–21; anal rays III, 9–11; and pectoral rays 19–23. The tail fin is strongly concave.
Adults reach about 36 centimeters in length. Juveniles are often bright yellow with five small dark spots on the back. Adults are greenish brown on top and reddish below, with five white or blue-white spots along the back; the fins are reddish.
This species ranges from the Gulf of California to Peru, including the Revillagigedo, Galapagos, Clipperton, Cocos Island, and Malpelo islands.
Like all fish, the Pacific creolefish hosts various parasites. Off Mexico, these include the digeneans Prodistomum orientalis, Brachyphallus sp., and Lecithochirium sp.; the nematodes Anisakis sp. and Spinitectus sp.; the copepod Caligus sp.; and the isopod Hatschekia sp. The diplectanid monogenean Pseudorhabdosynochus jeanloui was described from this fish off Peru in 2015.
Scientific classification
- KingdomAnimalia
- PhylumChordata
- Class
- DivisionTeleostei
- OrderPerciformes
- FamilyEpinephelidae
- GenusCephalopholis
- SpeciesCephalopholis colonus
Named by (Valenciennes, 1846)
Sources: Wikipedia taxobox: Cephalopholis colonus (CC BY-SA 4.0) · order, family and genus agree with WoRMS AphiaID 1750630 (CC BY 4.0)
Conservation status
Least Concern (LC)
- LC▲ this species
- NT
- VU
- EN
- CR
- EW
- EX
Source: IUCN Red List assessment · GBIF copy of the Red List category
How big is it?
Largest length in the source, 0.36 m, next to a 1.8 m person.
Diagram: drawn by Codexery, schematic shapes to scale (not a likeness). Length: Wikipedia: Cephalopholis colonus
Where the cephalopholis colonus has been recorded
Each dot is a place where the species has been observed and reported (1,015 records, half-degree grid) — not a modelled range. 21 inland records left out (institution coordinates).
Map: drawn by Codexery. Data: GBIF occurrence search (records CC0 / CC BY) · Natural Earth basemap (public domain) · place coordinates: Wikipedia (CC BY-SA 4.0)
Physical Form & Coloration
The Pacific creolefish presents a sleek, elongated fusiform body that distinguishes it from the bulkier guppies of its family. Its head is notably small, with both the dorsal and ventral profiles curving in a convex arc, while the tail fin is deeply concave, lending the fish a streamlined silhouette suited to active swimming. Adults reach roughly 36 cm in total length. Coloration shifts dramatically across life stages: juveniles flash a vivid yellow across their backs, punctuated by five small dark spots.
As they mature, the dorsal surface transitions to a muted greenish-brown while the belly takes on a warm reddish tone, and those five spots transform into white or blue-white markings. The fins themselves carry a reddish hue. Internally, the first gill arch bears between 37 and 44 rakers, the dorsal fin carries nine spines followed by 19 to 21 soft rays, the anal fin holds three spines and 9 to 11 rays, and the pectoral fins display 19 to 23 rays.
Feeding Ecology & Sensory Adaptation
The Pacific creolefish is a specialist planktivore that hunts in a manner quite distinct from many of its reef-dwelling grouper relatives. Rather than ambushing prey from cover, it forms large midwater schools specifically for feeding, picking individual small planktonic animals directly out of the open water column. This precise, close-range feeding strategy is made possible by a morphological adaptation: a shortened snout that allows the fish to achieve binocular vision at very short distances, enabling it to track and capture tiny drifting organisms with remarkable accuracy.
When not actively foraging, the species tends to gather in smaller aggregations positioned well above the reef structure. However, these open-water groupings are temporary; the moment a threat approaches, the fish retreats back toward the reef for protection. This behavioral pattern—expansive midwater feeding schools that collapse into reef shelter at the first sign of danger—highlights a species that balances the risks of open-water foraging with the security of complex coral and rock habitats.
Geographic Range & Habitat
The Pacific creolefish occupies a broad stretch of the Eastern Pacific Ocean, ranging from the Gulf of California southward to the coast of Peru. Within this corridor, the species is documented at several notable island groups, including the Revillagigedo archipelago, the Galápagos, Clipperton Island, Cocos Island, and the Malpelo islands. These scattered island habitats, combined with the continental shelf waters between them, provide the mix of open water and reef structure the fish requires.
In terms of vertical range, individuals have been recorded at depths reaching 100 meters, roughly 330 feet, though their typical behavior places them in the midwater zone above reefs during feeding periods. The distribution pattern suggests a species adapted to the varied currents and productivity of the Eastern Pacific, from the semi-enclosed waters of the Gulf of California to the more open, nutrient-rich currents surrounding the equatorial island chains.
Parasite Community & Taxonomic Discoveries
Like all fish species, the Pacific creolefish supports a diverse community of parasitic organisms, and its parasite fauna has proven a rich source of taxonomic discovery. Off the Mexican coast, researchers have identified a range of parasites in this species, including several digenean trematodes—Prodistomum orientalis, an undescribed Brachyphallus species, and a Lecithochirium species—alongside nematodes of the genera Anisakis and Spinitectus. Copepod and isopod crustaceans also make a living on or in the creolefish, represented by Caligus species and Hatschekia species, respectively.
Perhaps most notably, the diplectanid monogenean Pseudorhabdosynochus jeanloui was formally described in 2015 from specimens collected off Peru, underscoring that even well-studied Eastern Pacific fish continue to yield new species to science. The breadth of this parasite assemblage, spanning flatworms, roundworms, and crustaceans, reflects the creolefish's role as a stable host within its marine ecosystem.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Cephalopholis colonus (CC BY-SA 4.0).
- Classification: the source article's taxobox; order, family and genus checked against WoRMS, the World Register of Marine Species (CC BY 4.0).
- Conservation status: IUCN Red List assessment.
- Occurrence records: GBIF (CC0 / CC BY). Basemap: Natural Earth (public domain).
- Word definitions: the , each quoted from its Wikipedia article.
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