Longtail Jawfish, Lonchopisthus sinuscalifornicus

Longtail Jawfish, Lonchopisthus sinuscalifornicus. Fish provided by the commercial fishermen of Bahía Kino, Sonora, March 2015. Length: 21 cm (8.3 inches). Photograph and identification courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora.

The Longtail Jawfish, Lonchopisthus sinuscalifornicus, is a member of the Jawfish or Opistognathidae Family, and is known in Mexico as bocón cola larga. Globally, there are five species in the genus Lonchopisthus, of which two are found in Mexican waters, one in the Atlantic and this one in the Pacific Ocean.

The Longtail Jawfish has an elongated tapering body. Their head and body are tan or cream in color. Their body has thin blue bars at the front, a large intense blue-violet ocellus spot on the gill cover, and scattered blue spots behind the gill cover. Their anal and dorsal fins have a central row of blue spots and their pectoral fins are violet. They have a large bulbous head with large eyes that are set high on each side of the head and a large mouth that opens at the front and extends to the rear of the eyes. Their anal fin has 3 spines and 17 rays; their caudal fin is very long and thin (after which they are named); and their dorsal fin has 11 spines and 18 rays. The lateral line is only present on the first half of their body. They are covered with scales.

The Longtail Jawfish are found in relatively shallow water and live buried in sandy substrates at depths up to 53 m (175 feet). They reach a maximum of 30 cm (12 inches) in length. They live in elaborate burrows that are self-constructed by utilizing their mouths and powerful jaws to excavate sand, small stones, and medium-sized rocks and that they feed primarily on benthic and planktonic invertebrates. In addition, like other Jawfish, it is assumed that they exhibit the unusual habit of oral egg incubation.  The Longtail Jawfish 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 Longtail Jawfish is a resident of Mexican waters the Pacific but has a limited distribution being found in the lower two-thirds of the Sea of Cortez and along the coast of the mainland south to Guatemala. They are absent from the extreme northern portions of the Sea of Cortez and from the entire west coast of Baja.

The Longtail Jawfish cannot be confused with any other species due to its unique markings.

From a conservation perspective the Longtail Jawfish is currently considered to be of Least Concern with stable, widely distributed populations. They are too small and too obscure to be of interest to most.