Dusky Squirrelfish, Neoniphon vexillarium
Dusky Squirrelfish, Neoniphon vexillarium. Photograph taken underwater in coastal waters off Bonaire, December 2019. Photograph courtesy of Bob Hillis, Ivins, Utah.
The Dusky Squirrelfish, Neoniphon vexillarium, is a member of the Squirrelfish or Holocentridae Family, also known as the Blackbarred Squirrelfish and in Mexico as carajuelo oscuro. This species has recently been reclassified from the genus Sargocentron into the genus Neoniphon. Globally, there are twelve species in the genus Neoniphon, of which three are found in Mexican waters, two in the Atlantic and one in the Pacific Ocean.
The Dusky Squirrelfish has an ovate fusiform compressed body. The head and body are a brownish red with dark lines bordering wide silver stripes. The inside of the pectoral fin base is dark brown in adults and black in juveniles. The caudal fin has red upper and lower margins. The first dorsal fin is pink with a red spot between the spine tips, and the second dorsal fin is transparent. The head has a pointed snout, very large eyes, and a small oblique mouth. They have a series of slender spines under the eye, and 1 or 2 enlarged spines on the gill cover and a long stout spine at the corner of the preopercle. Their anal fin has 4 spines, with the third being long and stout, and 8 to 10 rays; their caudal fin is forked; their first dorsal fin has 11 spines; their second dorsal fin has 12 to 14 rays and is deep; their pectoral fins have 14 to 16 rays; and, their pelvic fins have 1 spine and 7 rays. They have 10 to 14 gill rakes. They are covered with large very rough scales.
Dusky Squirrelfish are found in and around shallow coral reefs and rocky structures as well as in tidal pools in the surge zone in depths up to 25 m (82 feet). They reach a maximum of 17 cm (6.7 inches) in length. They are generally solitary and nocturnal, hiding in crevices and caves during the daytime and emerging at night to hunt crabs, gastropods and shrimp. They are known to be preyed upon by the newly introduced highly invasive Red Lionfish, Pterois volitans. Reproduction is believed to involve batch spawning, with each female releasing eggs in open water that are fertilized externally. The pelagic eggs and larvae settle out in several weeks. The Dusky Squirrelfish 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 Dusky Squirrelfish is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico, with the exception that they are absent north of the State of Veracruz, and the east coast of the Yucatán Peninsula in the Caribbean.
The Dusky Squirrelfish can be confused with the Bigeye Soldierfish, Ostichthys trachypoma (red and white stripes about the lateral line; red and silver stripes below), the Deepwater Squirrelfish, Sargocentron bullisi (dark red with thin white stripes), the Longjaw Squirrelfish, Neoniphon marianus (orange dorsal fin with white spots), and the Reef Squirrelfish, Neoniphon coruscum (red body with thin white stripes).
From a conservation perspective, the Dusky Squirrelfish is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature and of limited interest to most, the exception being that they are seen with some frequency by underwater divers. They are a minor component of the aquarium trade.