Explore the Sonora coast of the Sea of Cortez at SeaSanCarlos and the Baja Peninsula at SeaBaja

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Sea of Cortez 810

Families Acanthuridae and Zanclidae
Surgeonfishes and Moorish Idol
Class: Actinopterygii (ray-finned)
Order: Perciformes

Key Features:
Acanthuridae:  A very deep body with strong lateral compression combined with a series of sharp spines on the caudal peduncle characterizes this family.  Most are solitary algae grazers, although there are some schooling varieties as well as more omnivorous species.  The mouth is small and terminal. 
Zanclidae:  Only a single genus with a single species comprises this family, the Moorish Idol.  Like the Surgeonfishes, Moorish idols are deep-bodied with strong lateral comprssion.   They have a long tubular snout and a striking dorsal filament that trails the fish.   Moorish idols lack the peduncular spine of surgeonfishes, but are otherwise very similar. 

Notable Species in the Sea of Cortez

Prionurus punctatus
Yellowtail Surgeonfish
Acanthurus triostegus
Convict Tang
Acanthurus xanthopterus
Yellowfin Surgeonfish
Acanthurus nigricans
Goldrimmed Surgeonfish
Zanclus cornutus
Moorish Idol

yellowtail surgeonfish prionurus punctatus, Photographed Scuba Diving in La Paz, Baja Mexico

Prionurus punctatus
Yellowtail Surgeonfish

La Paz, Baja California Sur, Mexico


Baja Mexico Scuba Diving, News, Animal Reports


San Carlos Scuba Diving, Sonora Mexico

Families Acanthuridae and Zanclidae
Surgeonfishes (Peces cirujanos) and Moorish Idol (Idolo moro)

The family Acanthuridae includes the surgeonfishes and the small family, Zanclidae, is comprised of Moorish idols.  Both are relatively uncommon in the Sea of Cortez as a whole, although some species may be locally abundant. 

The surgeonfishes are herbivorous fish that may be recognized by a sharp spine on the caudal peduncle that is used to slash predators and territorial interlopers.  The Moorish idol however, lacks spines on its caudal peduncle.  Within the Sea of Cortez there are only five species of surgeonfish within two genera.  Zanclidae contains only the Moorish idol, Zanclus cornutus.  All of these fishes become more common along Baja as one approaches the Cape region and may be quite common along Cabo San Lucas, Bahia Las Frailes and Cabo Pulmo. 

The only surgeonfish that scuba divers and snorkelers might observe with any frequency in the central Sea of Cortez is the yellowtail surgeonfish, Prionurus punctatus.  This species grows quite large up to about two feet and can be distinguished by identification of the three strong spines along the caudal peduncle, which are set against a grey body with yellow polka dots.  The bright yellow tail provides a brilliant contrast to the drab body.  Although it is often seen on the mainland Sonora side along Guaymas and San Carlos, especially at offshore islands such as Isla San Pedro Nolasco, it is comparatively more common at similar latitudes along the Baja coast. 



Updated August 28, 2009

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