Greater Sand Perch, Diplectrum maximum
The Greater Sand Perch, Diplectrum maximum, whose common Spanish name is serrano de altura, 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 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 (preopercle) with four to eight 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 nine 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 we caught. They are found in all Mexican 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 we caught. They are a deep water species and very little is known about their behavioral patterns.
The Greater Sand Perch is the easiest of the eight very similar Sand Perches, all of the Diplectrum Genus, living in Mexican waters of the Pacific, to identify. The key to correct identification is the unique shape of their peropercle. 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 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.