Spottail Pinfish, Diplodus holbrookii
Spottail Pinfish, Diplodus holbrookii, Juvenile. Fish caught from coastal waters off Cape Canaveral, Florida, July 2018. Length: 8.5 cm (3.3 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.
Spottail Pinfish, Diplodus holbrookii. Fish caught from coastal waters off Tampa, Florida, April 2011. Length: 20 cm (7.9 inches). Catch, photograph, and identification courtesy of Ryan Crutchfield, Tampa, Florida.
Spottail Pinfish, Diplodus holbrookii. Fish caught from coastal waters off Deerfield Beach, Florida, December 2020. Length: 20 cm (7.9 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.
Spottail Pinfish, Diplodus holbrookii. Fish caught from coastal waters off Marathon, Florida, July 2018. Length: 20 cm (7.9 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).
Spottail Pinfish, Diplodus holbrookii. Fish caught from the Indian River Lagoon, Fort Pierce, Florida, June 2020. Length 21 cm (8.3 inches). Catch and photograph courtesy of Doug Bomeisler, Fort Pierce, Florida.
The Spottail Pinfish, Diplodus holbrookii, is a member of the Porgy or Sparidae Family, and is known in Mexico as sargo cotonero. Globally, there are fourteen species in the genus Diplodus, of which two are found in Mexican waters, both in the Atlantic.
The Spottail Pinfish has an oval and compressed body with a depth that is 43% to 47% of standard length. Juveniles have five narrow vertical dark bars on their back and sides and an equal number of short intermediate bars on their back. Adults are steel blue dorsally and silvery on their sides; they have a large black spot just in front of their caudal peduncle that reaches the lower peduncle margin (a key to identification). The membranes of their gill covers are black. Their head has a pointed snout, a straight profile, and small eyes. They have a mid-sized terminal mouth that reaches the front margin of the eyes and is equipped with 6 well-developed incisiform teeth and 3 rows of lateral molariform teeth on each jaw. Their anal fin has 13 to 15 rays; their caudal fin is deeply forked; their dorsal fin has 12 or 13 spines and 13 to 16 rays; and, their pectoral fins are long. They have 17 to 21 short gill rakers on their first arch. They are covered with smooth scales. A key to the identification is that they longest dorsal spine is 40% of the head length.
The Spottail Pinfish is a schooling species found in shallow seagrass flats, eelgrass beds, breakwaters, jetties, piers, wharf pilings, and areas of sparse vegetation on sandy or muddy bottoms at depths up to 76 m (250 feet). They reach a maximum of 35 cm (14 inches) in length and 1.2 kg (2 lbs 10 oz) in weight. They are found mixed in with other species in water temperatures between 17.5oC (64oF) and 32.5oC (91oF) with high salinities and never in freshwater environments. Juveniles are normally found in shallow waters. They move to deeper waters around natural and artificial reefs and man-made platforms during warm water episodes and in winter as they mature. They are daytime feeders that consume plant materials and animals attached to plants including algae, plankton, copepods, small crabs, mollusks, small shrimp, as well as ectoparasites they obtain by cleaning other fish. They are a vital component of the marine ecosystem and are preyed upon by various barracuda, flatfish, groupers, porgies, seatrouts, snappers, and snooks. Reproduction is believed to occur via protandrous hermaphroditism. Fertilization is external with pelagic eggs and larvae. They have a lifespan of up to eleven years.
The Spottail Pinfish is a resident of Mexican waters of the Atlantic Ocean but is limited to the western and southwestern Gulf of Mexico and normally found in deeper waters.
The Spottail Pinfish is most likely confused with the Silver Porgy, Diplodus argenteus (dark spot on caudal peduncle does not extend to peduncle margin; longest dorsal spine is 40% of the head length).
From a conservation perspective the Spottail Pinfish is currently considered to be of Least Concern with stable, widely distributed populations. They are subject to habitat destruction and overfishing in some parts of their range. They are considered to be an excellent food fish, although small in stature, and caught as a by-catch by both commercial and recreational fishermen utilizing gill nets, hook and line, longlines, seines, bottom trawls and fish traps. They are known to contain ciguatoxin. They are unregulated in most parts of their range (except for coastal waters of the southeast United States) and commercial landings have declined significantly in the last 10 years. They are used on a limited basis as live bait fish.