Black Wrasse, Halichoeres adustus

Black Wrasse, Halichoeres adustus, Initial Phase (IP), Female. Underwater photograph taken in Zihuantanejo, Guerrero, February 2019. Photograph courtesy of Ron Woheau, Zihuantanejo.

Black Wrasse, Halichoeres adustus, Initial Phase (IP), Female, Transitioning To A Terminal Phase (TP), Male. Underwater photographs taken in Zihuantanejo, Guerrero, February 2019. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Black Wrasse, Halichoeres adustus, is a member of the Wrasse or Labridae Family, and is known in Mexico as señorita negra. Globally, there are seventy species in the genus Halichoeres, seventeen of which are found in Mexican waters, ten in the Atlantic and seven in the Pacific Ocean.

The Black Wrasse have elongated compressed bodies. Juveniles are a dark gray-brown color with a lighter colored breast and head and they are covered with numerous small blue or white spots arranged in longitudinal rows; they have a white bar posterior of the pectoral fin, a white edged black spot on the middle of the dorsal fin and several white blotches on their sides. Females (Initial Phase) are a dark gray-brown color with a lighter colored breast and head and they are covered with numerous small blue or white spots arranged in longitudinal rows; the caudal fin has a broad white margin. Males (Terminal Phase) are a uniform dark brown or black with narrow blue fin margins. Their mouth has 1 pair of large canines at the front of the upper and 2 pairs at the front of the lower jaw and another at the rear of the top jaw. Their anal fin has 3 spines and 12 rays; their dorsal fin has 9 spines and 11 rays; and, their pectoral fins have 12 rays. Their lateral line is continuous but bent downward at the rear of the dorsal fin.

The Black Wrasse are found in rock reef areas at depths up to 5 m (15 feet). They reach a maximum of 12.5 cm (5.0 inches) in length. They are exceedingly rare small shallow-water species that are seldom seen by humans. The Black Wrasse is poorly studied and very little is known about their behavioral patterns.

The Black Wrasse is a resident of Mexican waters of the Pacific Ocean but has a very limited range that includes the Tres Marias Islands, and as a vagrant in the greater Cabo San Lucas area of Baja California Sur. The photographs above document the presence of the Black Wrasse in the coast waters along the southwest coast of the mainland.

The Black Wrasse cannot be easily confused with any other species with the possible exception of the Terminal Phase (TP) Male Banded Wrasse, Halichoeres notospilus (bars on the sides).

The Black Wrasse are exceedingly rare, small and of limited interest to most. From a conservation perspective, they are considered to be VULNERABLE, due to only known breeding location being the Cocos Island, and rising sea water temperatures with strong El Niño episodes have had documented detrimental effects on the survival of this species.