Highfin Sand Perch, Diplectrum labarum
The Highfin Sand Perch, Diplectrum labarum, whose common Spanish name is serrano espinudo, is a species in the Family Serranidae, the Sea Bass, known as serranos in Mexico. Globally, there are twelve species in the genus Diplectrum, of which ten 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 (preopercle) 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 five or six 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. They reach a maximum length of 26 cm (10 inches). In Mexican waters they are found south of Guerrero Negro along the Pacific side of the Baja, throughout the Sea of Cortez, and along the coastal mainland south to Guatemala. They are a small and rare deep-water species and very little is known about their behavioral patterns.
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. A key to the identification is the shape of the peropercle, as presented below. Sand Perch Preopercles – for an interesting look at some fish anatomy of some very similar looking fishes of the Diplectrum Genus you can see the preopercles of seven Sand Perches found in the Pacific side-by-side.
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.