Highfin Sand Perch, Diplectrum labarum
The Highfin Sand Perch, Diplectrum labarum, whose common Spanish name is serrano espinudo, is a species in the Sea Bass or Serranidae Family, known collectively as serranos in Mexico. Globally, there are twelve species in the genus Diplectrum, ten of which are found in Mexican waters, two in the Atlantic and eight in the Pacific.
The Highfin Sand Perches have long slender bodies with an overall gray-brown coloration and a silvery-white belly. Their head has a blunt snout with a slightly projecting lower jaw and a narrow squarish bony cheek spur (preoperculum) that is wider than long that has 8 to 13 large spines (pictured below), a key to identification. The species has a series of yellow lines: two on their anal fin, five on their caudal fin, one under their eyes, one on their dorsal spine, and six on their dorsal rays. They also have a purple spot on their gill covers and a black spot at the base of their tail. They have a series of 5 or 6 squarish dark blotches on their upper sides. The second to fourth dorsal spines are longer than the others and feature black filaments; the second spine is at least twice as long as the first. Their anal and dorsal fins are transparent, their pelvic fins are yellow, and their pectoral fins are yellow with red stripes. Their caudal fin is concave with a longer upper lobe.
The Highfin Sand Perches are found over sandy bottoms at depths between 75 and 500 feet. The maximum length for this species is 28.9 cm (11.4 inches) established by a fish I caught with Jimmy Camacho, Jimmy’s Sportfishing, Puerto Adolfo Lopez Mateos, Baja California Sur, (Jimmy Camacho Jimmyhcamacho@gmail.com, 613-114-0761; 612-204-1960) in May 2017. They are a small and rare deep-water species and very little is known about their behavioral patterns.
In Mexican waters they are found from Guerrero Negro southward along the central and southwest coasts of Baja, throughout the Sea of Cortez, and along the coastal mainland south to Guatemala.
The Highfin Sand Perch is exceedingly difficult to correctly identify because there are eight very similar Sand Perches, all of the Diplectrum Genus, living in Mexican waters of the Pacific. The key to a correct identification is the unique shape of the preoperculm. See Sand Perch Preoperclum for an interesting side-by-side look at some fish anatomy of seven very similar looking fishes of the Diplectrum Genus found in the Pacific.
The Highfin Sand Perch is fairly common and can become a pest at certain times of the year and in certain locations. They are too small to be of interest to most, however they will be retained by subsistence fishermen. When released, they will not return to the deep and are almost immediately consumed by the Magnificent Frigate Bird, Fregata magnificus, providing for splendid visual entertainment.
Highfin Sand Perch, Diplectrum labarum. Fish caught from coastal waters off Point Palmilla, Baja California Sur, November 2013. Length: 25.8 cm (10.2 inches). Fish identification courtesy of Dr. Ross Robertson, Smithsonian Institute, Panama.