Bridled Sand Perch, Diplectrum rostrum
Bridled Sand Perch, Diplectrum rostrum, Juvenile. Fish caught from coastal waters of Point Palmilla, Baja California Sur, July 2017. Length: 15 cm (5.9 inches). Note the diminished markings and coloration compared to the adult fish below.
Bridled Sand Perch, Diplectrum rostrum. Fish caught from coastal waters of Point Palmilla, Baja California Sur, July 2017. Length: 19 cm (7.5 inches). Note the enhanced markings and coloration compared to the juvenile fish above.
Bridled Sand Perch, Diplectrum rostrum: preoperculum.
The Bridled Sand Perch, Diplectrum rostrum, is a member of the Sea Bass or Serranidae Family, and is known in Mexico as serrano frenado. 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 Ocean.
The Bridled Sand Perche has a long slender body with an overall tan color, a white belly, and a head covered with yellow-orange stripes. Their head features a narrow bony cheek spur (preoperculum) with 7 to 11 spines (pictured above) that is a key to identification. They have 5 to 7 dark bars on their sides, an indistinct black mid-lateral stripe, 2 black spots at the base of their symmetrical tail fin, 2 pink bars and a yellow ring under their eyes, and a gray tail with clear spots.
The Bridled Sand Perch is found over sandy bottoms at depths between 15 m (50 feet) and 88 m (288 feet). This maximum depth was established by a fish I caught in July 2016. They reach a maximum of 26 cm (10.4 inches) in length, as documented by a fish that I caught. The Bridled Sand Perch are synchronously hermaphroditic possessing both males and female organs and capable of producing eggs and sperm at the same time. They spawn in deep water as mating pairs. Their eggs and larvae are pelagic and move to shallower waters as they mature. The Bridled Sand Perch is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Bridled Sand Perch is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found from Magdalena Bay, Baja California Sur, southward along the southwest coast of Baja, in the southern half of the Sea of Cortez, and along the coastal mainland south to Guatemala.
The Bridled Sand Perch is difficult to correctly identify because there are eight very similar Sand Perches, all of the Diplectrum Genus, living in Mexican waters of the Pacific Ocean. The key to a correct identification is the unique shape of the preoperclum. See Sand Perch Preoperculum 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 Ocean.
From a conservation perspective the Bridled Sand Perch is currently considered to be of Least Concern with stable widely distributed populations. They are too small to be of interest to most. They are fairly abundant in the greater Los Cabos area and efforts at “catch and release” normally do not go well as they will not return to the deep and float on the surface and are almost immediately consumed by the ever vigilant Magnificent Frigate Bird, Fregata magnificus, who post consumption, will always return to the ocean for drinks of water, providing for splendid entertainment.