Bridled Sand Perch, Diplectrum rostrum
The Bridled Sand Perch, Diplectrum rostrum, whose common Spanish name is serrano frenado, 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 Bridled Sand Perches have long slender bodies 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 below); the shape of their head is a key to identification. They have 5 to 7 dark bars on their sides, an indistinct black mid-lateral stripe, two black spots at the base of their symmetrical tail fin, two pink bars and a yellow ring under their eyes, and a gray tail with clear spots.
The Bridled Sand Perches are found over sandy bottoms at depths between 50 and 288 feet. This maximum depth was established by a fish I caught in July 2016. They reach a maximum length of 26 cm (10.4 inches), as documented by a fish that I caught. They are a small and rare deep water species and very little is known about their behavioral patterns.
In Mexican waters the Bridled Sand Perch has a limited distribution being found from Magdalena Bay 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 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. 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 Bridled Sand Perch is too small and too rare to be of interest to most.
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, juvenile: preoperclum.
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: preoperclum.