Pacific Cutlassfish, Trichiurus nitens

Pacific Cutlassfish, Trichiurus nitens. Fish caught with the Puerto Los Cabos Marina, Baja California Sur, May 2008. Length: 54 cm (21 inches). Catch courtesy of Eric Brictson, Gordo Bank Pangas, Puerto Los Cabos, Baja California Sur.

Pacific Cutlassfish, Trichiurus nitens. Fish caught from coastal waters off Mazatlán, Sinaloa, May 2021. Length: 70 cm (2 feet 4 inches). Photograph courtesy of Jason Potts, Mazatlán.

Pacific Cutlassfish, Trichiurus nitens. Fish provided by the commercial fishermen of Bahía Kino, Sonora, March 2015. Length: 85 cm (2 feet 9 inches). Photograph and identification courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora.

Pacific Cutlassfish, Trichiurus nitens. Head recovered from the stomach of a 62 cm (2 feet 0 inches) Black Skipjack, Euthynnus lineatus, February 2024. Length: 21 cm (8.3 inches).  Catch, photograph and identification courtesy of Chip Shapley, Los Barilles, Baja California Sur.

The Pacific Cutlassfish, Trichiurus nitens, is a member of the Cutlassfish or Trichiuridae Family, and is known in Mexico as sable del Pacifico. Globally, there are three species in the genus Trichiurus, of which two are found in Mexican waters, one in the Atlantic and one in the Pacific Ocean.

The Pacific Cutlassfish has an extremely elongated and strongly compressed ribbon-like body that tapers to a point. They have a uniform silvery appearance being darker blue on their upper back and transitioning to silvery reflections ventrally with yellowish transparent fins. Their head has a long snout and large eyes. They have a projecting lower jaw with a large mouth equipped with 2 or 3 pairs of large fangs and a series of sharp and compressed lateral teeth on both jaws. Their anus is closer to the tip of the snout than to the tip of the tail. Their anal fin has 100 to 105 rays which are exceedingly small and usually embedded in the skin; their first dorsal fin is high with a long base, 3 spines and 130 to 135 rays; and, their pectoral fins are mid-sized. They do not have caudal or pelvic fins. Their lateral line begins at the upper margin of the gill cover, runs oblique to reach behind the tip of the pectoral fins, then continues straight across the ventral contour. They do not have scales.

The Pacific Cutlassfish is a rare and poorly studied species and believed to be benthopelagic and amphidromous. They are found in both marine and brackish environments over muddy bottoms of shallow coastal waters and in estuaries from the surface to depths up to 384 m (1,260 feet). They reach a maximum of 1.2 m (4 feet 0 inches) in length. They are vertical migrators with adults feeding near the surface on crustaceans, fish, and squid and during the daytime and they retreat to the bottom at night. Juveniles form schools and feed planktonic organisms near the surface. They are known to migrate seasonally to wintering and spawning grounds. Reproduction is via dioecism with each female releasing up to 130,000 eggs per year which are fertilized externally by males. The eggs are scattered on the substrate and the subsequent pelagic larvae hatch in 3 to 6 days. The Pacific Cutlassfish 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 Cutlassfish is a resident of all Mexican waters of the Pacific Ocean.

The Pacific Cutlassfish is very similar to the Atlantic Cutlassfish, Trichiurus lepturus (larger eyes; shorter upper jaw; shorter snout) and can also be confused with the Black Snake Mackerel, Nealotus tripes and the Snake Mackerel, Gempylus serpens, both of which have well-defined forked tails.

From a conservation perspective the Pacific Cutlassfish has not been formally evaluated. They are too rare to be of interest to most but if available are considered to be an “excellent” food fish when fried or grilled.