Rockmover Wrasse

Rockmover Wrasse, Novaculichthys taeniourus

The Rockmover Wrasse, Novaculichthys taeniourus, whose common Spanish name is cuchillo dragón, is a member of the Wrasse or Labridae Family, known collectively as doncellas, señoritas, and viejas in Mexico. Their common name is derived from their behavior of turning over rocks seeking prey. Juveniles are known as the Dragon Wrasse. The Rockmover Wrasse is a truly gorgeous fish. Globally, there are four species in the genus Novaculichthys, of which one is found in Mexican waters of the Pacific and is described here.

The Rockmover Wrasses have elongated, oblong, and very compressed bodies. Juveniles (IP) are mottled with green, red or brown bands and are covered with white spots; they have brown lines radiating from their eyes and a pink belly. Adults (TP) are greenish-brown with a white spot on each side of their head; their anal and dorsal fins are black and their caudal fin is black with a white base. They lack the radiating lines from the eyes and the pink belly found in juveniles and have a yellow spot at the base of their pectoral fin. Their head is off-white and wedged-shaped. They have medium-sized eyes set high on their head and a mid-sized terminal mouth that opens in the front. They are equipped with two pairs of short canines at the front of their upper and lower jaws. Their anal fin has three spines and 12 or 13 rays and their dorsal fin has nine spines and 12 or 13 rays; the first two spines are greatly elongated in juveniles. Their lateral line is broken into two parts and they have no scales on their head.

The Rockmover Wrasses are a benthopelagic species found in shallow semi-exposed reef flats, in lagoons, and in seaward reefs in waters between 24oC (75oF) and 28oC (83oF) at depths between 45 and 80 feet. They reach a maximum length of 30 cm (12 inches). They prefer hard-bottomed grassy areas of mixed sand and rubble exposed to mild surge and will reside in sand at night. Juveniles are found in shallow areas on rubble among large patch reefs and will mimic floating algae. They travel in pairs feeding on benthic invertebrates including brittle stars, crabs, mollusks, polychaete worms, and sea urchins, often working to dislodge food. They are highly territorial. They have the ability to quickly submerge themselves in sand as a defense mechanism. Reproduction is poorly understood but is believed to occur via protogynous sequential hermaphroditism with individuals beginning life as either male or female and females changing to males later in life. They are oviparous with broadcasted eggs that are fertilized externally. Eggs and larvae are pelagic.

The Rockmover Wrasses have a wide distribution in the tropical Indian and Pacific Oceans. In Mexico, they have a limited distribution and are found from La Paz to Cabo San Lucas along the east coast of Baja and from the Central Gulf southward to Guatemala along the west coast of the mainland.

The Rockmover Wrasse is straightforward to identify and cannot be confused with any other species.

The Rockmover Wrasses are a popular aquarium fish due to their beautiful coloration and hardiness, however, they are semi-aggressive and require large tanks and moderate care. They are known as escape artists. From a conservation perspective, they are considered of Least Concern, being common and found over a wide range. They are prone to coral reef destruction and local endangerment. They are sold fresh on a limited basis and retained by subsistence fishermen.

Rockmover Wrasse, Novaculichthys taeniourus, Juvenile. Underwater photo taken in coastal waters off Kailua-Kona, HI, April 2015. Length: 7.6 cm (3.0 inches). Photo courtesy of Bob Hillis, Ivins, UT.

Rockmover Wrasse, Novaculichthys taeniourus. Underwater photo taken in coastal waters off Kailua-Kona, HI, February 2015. Length: 23.0 cm (9.0 inches). Photo courtesy of Bob Hillis, Ivins, UT.