Dwarf Sand Perch, Diplectrum bivittatum
Dwarf Sand Perch, Diplectrum bivittatum. Both fish caught from coastal waters off Silver Palm Park, Boca Raton, Florida, February 2016. Length: 11.4 cm (4.5 inches) and 10.1 cm (4.0 inches), respectively. Catch, photographs and identification courtesy of George Brinkman, Guelph, Ontario, Canada.
The Dwarf Sand Perch, Diplectrum bivittatum, is a member of the Sea Bass or Serranidae Family, and is known in Mexico as serrano guabino. 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. This is one of the two Sand Perches found in the Atlantic Ocean and it is by far the smallest.
The Dwarf Sand Perch has an elongated slender slightly compressed body with very similar dorsal and ventral profiles and their head has a large mouth and large eyes. They are pale brown on their back and sides and fade to white ventrally. They have a dark stripe that runs just under their dorsal fin and a second stripe that runs from the snout, through the eye, to the caudal fin base. They have nine to eleven vertical yellowish-brown to tan bars on their sides. They have three light blue lines on their cheek and under their eyes. Juveniles have two broad dark stripes, one from the gill cover to the caudal fin base and the other just above, that end in a dark blue or white-edged spot. Their preoperculum has one cluster of radiating spines. Their anal fin has 3 spines and 6 to 8 rays; their caudal fin is concave with the upper lobe having an elongated second ray; their dorsal fin has 10 spines and 11 to 13 rays and is low; their pectoral fins have 14 to 16 rays; and their pelvic fins originate under the pectoral fins. They are covered with small rough scales. They have a complete lateral line.
The Dwarf Sand Perch is a common and abundant species found in shallow bays over sandy bottoms and muddy silt at depths up to 114 m (375 feet). They reach a maximum of 25 cm (10 inches) in length. They feed primarily on benthic shrimps. In turn they are preyed upon by larger fish and are an important food source for drums, groupers, porgies, sharks, snappers, and various sea birds. The Dwarf 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 shallow waters as they mature. The Dwarf 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 Dwarf Sand Perch is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.
The Dwarf Sand Perch cannot be easily confused with any other species due to the two strong stripes on its sides. In body structure and size, it is similar to the other Sand Perches of the Diplectrum genus and the Sea Basses of the Centropristis genus found in Mexican waters of the Atlantic Ocean.
From a conservation perspective the Dwarf Sand Perch is currently considered to be of Least Concern with stable widely distributed populations. They are too small in statue and of interest to most. They are a fairly significant by-catch of the shrimp trawl fishery. They can be used as live bait for larger fish. They are caught by hook and line on cut bait from shores, bridges, and small boats. They are generally unfriendly towards divers.