Greater Sand Perch, Diplectrum maximum
The Greater Sand Perch, Diplectrum maximum, whose common Spanish name is serrano de altura, 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 Greater Sand Perches have elongated bodies with an overall tan coloration and a white belly. Their head is dark gray-brown in its upper two-thirds and features a narrowly pointed and rounded bony cheek spur (preoperculum) with 4 to 8 large spines (pictured below) that is a key to their identification. Their lower jaw is strongly projecting. They have a dark blue-gray blotch on the upper edge of their gill cover. The second and third dorsal spines are of equal length. Juveniles have a black spot in the membrane between their first and second dorsal spines. Their anal fin is gray, their caudal fin is gray-brown, their dorsal fin features blue-gray and red-brown bands with red-brown margins, their pectoral fins are translucent yellowish-brown, and their pelvic fins are dark gray.
The Greater Sand Perches are found over sandy bottoms at depths between 200 and 400 feet. They are the largest of the 9 Sand Perches found in Mexican waters of the Pacific and reach a maximum length of 45 cm (17.7 inches) and can weigh up to 1.5 kg (3.3 pounds), as documented by a fish that I caught. They are a deep water species and very little is known about their behavioral patterns.
In Mexican waters the Greater Sand Perch are found in all waters of the Pacific and were thought to be absent from the Sea of Cortez, however, they are actually very abundant along the southeast coast of Baja as documented by numerous fish that I have caught.
The Greater Sand Perch is the easiest to identify of the 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 preoperclum. 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 Greater Sand Perch is one of the very best bottom fish for human consumption that is caught in Mexican waters. They are sold extensively in local fish markets. Their roe is considered to be a delicacy. They are the only Sand Perch that we are aware of that when hauled up from the deep will return to the deep on their own. They consume a variety of small fish, which are frequently regurgitated and found on the panga floor or in the fish box.
Greater Sand Perch, Diplectrum maximum, Juvenile. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, May 2011. Length: 20 cm (7.9 inches). Note the black spot between the first and second dorsal spines.
Greater Sand Perch, Diplectrum maximum, Juvenile. Fish caught from coastal waters off Puerto Adolfo Lopez Mateos, Baja California Sur, July 2016. Length: 16 cm (6.3 inches).
Greater Sand Perch, Diplectrum maximum, Pugheaded. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, January 2010. Length: 36 cm (14.2 inches). A fish with a rare condition known as “pugheaded.”