Mexican Sand Perch, Diplectrum macropoma
The Mexican Sand Perch, Diplectrum macropoma, whose common Spanish name is Serrano Mexicano, is a member of the Sea Bass or Serranidae Family, known collectively as “serranos” in Mexico.
The Mexican Sand Perch has an elongated body with an overall pale cooper to light brown coloration with a white belly, and a series of characteristic markings including two rows of thin dark bars on the sides, a large dark spot at the base of the tail, a series of faint yellow bars under the eyes and a purple spot on the gill covers. The head has a narrow bony cheek spur (preoperculum) with eight to thirteen long spines (as pictured below), whose shape is a key to identification. All of the fins are clear with the exception that the upper portion of the caudal fin and the pectoral fins are yellow. The anal fin has a very narrow yellow stripe near the edge and the caudal fin has three yellow stripes. The dorsal fin has a continuous yellow stripe running its length and a row of spots near the perimeter which are faint in the spiny portion and prominent in the rayous portion. A key to identification is that dorsal spines one to four increase proportionally stepwise in length.
The Mexican Sand Perch are found over sandy bottoms at depths between 30 and 400 feet. They reach a maximum length of 28.8 cm (11.3 inches), documented by a fish that we caught. In Mexican waters the Mexican Sand Perch is found from Magdalena Bay south along the Pacific side of Baja, throughout the Sea of Cortez, and along the coastal mainland south to Guatemala. They are a small, rare, deep water species and not much is known about their behavioral patterns.
The Mexican Sand Perch is difficult to correctly identify because there are eight very similar Sand Perches, all of the Diplectrum Genus, that live in Mexican waters of the Pacific. The key to a correct identification is the unique shape of the peroperculum. In addition to the Mexican Sand Perch we present five additional Sand Perches: the Bighead Sand Perch, Diplectrum euryplectrum; the Bridled Sand Perch, Diplectrum rostrum; the Greater Sand Perch, Diplectrum maximum; the Highfin Sand Perch, Diplectrum labarum; and the Pacific Sand Perch, Diplectrum pacificum. There are two additional Sand Perches found in Mexican waters of the Pacific that we are seeking: the Orange-Spotted Sand Perch, Diplectrum eumelum (maximum length 31 cm – 12.2 inches, preoperculum wide with eight to fourteen long spines, face large covered with orange spots and stripes, caudal fin with bars of orange spots); and the Squirrel Sand Perch, Diplectrum sciurus (maximum length 17 cm – 6.7 inches, preoperculum square with five to ten large spines, body with two dark stripes and eight to ten dark bars, dorsal fin with two to three rows of yellow spots).
The Mexican Sand Perch is too small and too rare to be of interest to most.