Choelo Halfbeak, Hyporhamphus gilli

Choelo Halfbeak, Hyporhamphus gilli. Fish provided by commercial bait salesmen from Puerto Los Cabos, Baja California Sur, September 2007. Length: 18 cm (7.1 inches). Fish identification reconfirmed by H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, California.

Choelo Halfbeak, Hyporhamphus gilli. Fish provided by commercial bait salesmen from Puerto Los Cabos, Baja California Sur, September 2016. Length: 20 cm (7.9 inches).

The Choelo Halfbeak, Hyporhamphus gilli, is a member of the Halfbeak or Hemiramphidae Family, and is known in Mexico as pajarito cholo. Globally, there are thirty-six species in the genus Hyporhamphus, of which six are found in Mexican waters, three in the Atlantic and three in the Pacific Ocean.

The Choelo Halfbeak has an elongated cylindrical slender body. They are silvery brown dorsally with dark-edged scales and silvery ventrally and on their sides. Their upper back has three narrow dark stripes and their mid-flank has a distinct gray stripe with a black upper border. Their snout and beak are black with a red tip. Their fins are transparent to dusky. Their lower jaw extends into a relatively short beak that is less than twice the head length and their upper jaw is short and triangular. They have no teeth. Their anal fin has 15 to 18 rays and originates behind the dorsal fin; their caudal fin is moderately forked with the lower lobe being larger than the upper lobe; their dorsal fin has 14 or 15 rays; their pectoral fins are short and high on the sides; and, their pelvic fins are on the abdomen well back on the body with the origin being closer to the pupil than to the caudal fin base. Their anal and dorsal fins are well back on the body with bases opposite each other. They have 37 to 50 gill rakers. They are covered with large smooth scales. Their lateral line is low on the body.

The Choelo Halfbeak is a pelagic species normally found in coastal waters on the surface to depths of 6 m (20 feet). They reach a maximum of 21.0 cm (8.3 inches) in length. They feed on small fish and plankton. In turn they are preyed upon by birds, dolphins, dorado, marlins, porpoises, squids, and tuna. Reproduction is oviparous with females releasing large eggs containing a sticky substance that allows the eggs to attach to floating debris. The Choelo Halfbeak 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 Choelo Halfbeak is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found from Guerrero Negro, Baja California Sur, southward along the central and southwest coasts of Baja, in the southern half of the Sea of Cortez, and along the coast of the mainland south to Guatemala.

The Choelo Halfbeak can be easily confused with the California Halfbeak, Hyporhamphus rosae (lower bill dark red), the Longfin Halfbeak, Hemiramphus saltator (25 to 32 gill rakers), and the Pacific Silverstripe Halfbeak, Hyporhamphus naos (29 to 39 gill rakers, caudal fin modestly forked).

From a conservation perspective the Choelo Halfbeak is currently considered to be of Least Concern with stable, widely distributed populations. They are  limited interest to most.