Pacific Argentine, Argentina sialis

Pacific Argentine, Argentina sialis. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, June 2011. Length: 12 cm (4.7 inches). Identification courtesy of H.J. Walker, Jr., Scripps Institute of Oceanography, La Jolla, California.

Pacific Argentine, Argentina sialis. Fish caught off the La Ribera Bank, East Cape, Baja California Sur, January 2018. Length: 16.5 cm (6.5 inches). Catch and photography courtesy of Brad Murakami, Surrey, British Columbia, Canada.

The Pacific Argentine, Argentina sialis, is a member of the Argentine or Argentinidae Family, and is known in Mexico as argentina de Pacifico. Globally, there are twelve species in the genus Argentina, of which two are found in Mexican waters, one in the Atlantic and one, this species, in the Pacific Ocean.

The Pacific Argentine has an elongated compressed body. They are silvery in color with an iridescent silver stripe along their back and a black blotch above their eyes, 8 faint dusky bars on their back, and dusky fins. Their head is short with a long pointed snout, a small mouth that opens at the front, and small eyes. Their fins are spineless. Their adipose fin is small and above the anal fin; their anal fin is small with 11 to 25 rays; their single dorsal fin is located at the center of the body with 10 to 14 rays; their caudal fin is strongly forked; their pectoral fins are low on the sides; and their pelvic fins have 10 to 15 rays. They have less than 8 short robust gill rakers. Their body is covered with small smooth scales.

The Pacific Argentine is found in coastal waters over soft bottoms at depths between 14 m (45 feet) and 914 m (3,000 feet). They reach a maximum length of 22.0 cm (8.7 inches). The Pacific Argentine  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 Pacific Argentine is a resident of all Mexican waters of the Pacific with the exception that they are absent from Guadalajara, Jalisco, southward along the coast of the mainland to Guatemala.

The Pacific Argentine is a straightforward identification due to its body profile and is thus unlikely to be confused with other fish.

From a conservation perspective the Pacific Argentine is currently considered to be of Least Concern with widely distributed stable populations. They are seldom seen by humans; the specimens photographed above are rare catches via hook and line.