Sand Perch, Diplectrum formosum

Sand Perch, Diplectrum formosum. Fish caught from coastal waters off Miami, Florida, February 2022. Length: 10 cm (3.9 inches). Catch, photograph and identification courtesy of James Lafontaine, Long Island, New York.

Sand Perch, Diplectrum formosum. Fish caught from coastal waters off Clearwater, Florida, March 2012. Length: 10 cm (3.9 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Sand Perch, Diplectrum formosum. Fish caught from within the Phil Foster Park, Riviera Beach, Florida, June 2023. Length: 11.5 cm (4.5 inches). Catch, photograph and identification courtesy of Chris Moore, Peoria, Arizona.

Sand Perch, Diplectrum formosum. Fish caught from coastal waters off Key Largo, Florida, August 2014. Length: 16 cm (6.3 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.

Sand Perch, Diplectrum formosum. Fish caught from coastal waters off Key West, Florida, August 2014. Length: 26 cm (10 inches). Photograph courtesy of Dean Kimberly, Atlanta, Georgia.

Sand Perch, Diplectrum formosum. Fish caught from coastal waters off Key Largo, Florida, April 2019. Length: 26 cm (10 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

The Sand Perch, Diplectrum formosum, is a member of the Sea Bass or Serranidae Family, and is known in Mexico as serrano arenero. 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 Ocean. This is one of the two sand perches found in the Atlantic Ocean and is by far the largest.

The Sand Perch has an elongated slender slightly compressed body with very similar dorsal and ventral profiles. They are pale brown on the back and sides, fading to white ventrally. They have five to seven vertical bars that are yellowish-brown to tan. They also have a conspicuous dark mid-body stripe, ending in a dark spot on the upper half of their caudal fin base. They have the ability to change this stripe color from pale to dark very quickly. They have bright blue lines across their head and body and some individuals have orange and blue shading on their sides. All their fins are dusky with the caudal fin also having light orange blotches and the dorsal fin having longitudinal blue and yellow lines. Their head, eyes, and mouth are large. Their preoperclum has two clusters of numerous sharp long spines. Their anal fin has 3 spines and 7 or 8 soft rays; their caudal fin is concave with the upper lobe being larger than the lower lobe; their dorsal fin has a long base with 10 spines and 12 rays and is continuous without a notch; and, their pelvic fins are long and originate before or under the pectoral fins.

The Sand Perch is found in shallow bays within seagrass beds at depths up to 201 m (660 feet). They reside in holes in sandy bottoms or under rocks. They reach a maximum of 30 cm (12 inches) in length. They feed primarily on benthic crustaceans including amphipods, crabs, and shrimps as well as small fish. They are preyed upon by larger fish and are an important food source for drums, groupers, porgies, sharks, snappers, and various sea birds. The 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. They are a non-schooling species with lifespans of six or seven years. The 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 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 Sand Perch can be confused with the Dwarf Sand Perch, Diplectrum bivittatum (only one set of spines on preoperclum; triangular black spot on  upper gill cover; irregular vertical dark bars on sides).

From a conservation perspective the Sand Perch is currently considered to be of Least Concern with stable widely distributed populations. They are fished both commercially and recreationally although they give a poor fight due to their small size. They are considered an excellent food fish. They are also 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 unfriendly towards divers.