Pricklebreast Poacher, Stellerina xyosterna

Pricklebreast Poacher, Stellerina xyosterna. Fish caught from coastal waters off Carmel, California, October 2026. Length: 16 cm (6.3 inches). Catch and photographs courtesy Darren Wong, Fremont, California. Identification courtesy of Zachary Fratello, Redondo Beach, California.

The Pricklebreast Poacher, Stellerina xyosterna, is a member of the Poacher or Agonidae Family, and is known in Mexico as bandido pecho espinoso. The Agonidae Family includes alligatorfishes, hooknoses, Irish-lords, poachers, rockheads, sea ravens, and starsnouts and includes forty-six species, in twenty-one genera. The Pricklebbreast Poacher is the only species of the Stellerina Genus.

The Pricklebreast Poacher has a slender elongated body with a spiny flattened head. They are a plain brown color with dark mottling or black spots that matches the substrate in which they reside. Their anal fin has 9 rays; their caudal fin is rounded; their dorsal fin has 9 spines and 6 rays; their pectoral fins are broad, large and fan like; and, their pelvic fins are small. Their scales are heavily encased in overlapping bony armor plates.

The Pricklebreast Poacher is a bottom dweller that is found over sand and muddy substrate at depths up to 100 m (330 feet). They reach a maximum of 16.5 cm (6.5 inches) in length. They are primarily nocturnal and solitary taking shelter during daylight hours. They lack a swim bladder and utilize their large pectoral fins to “hop” or scoot in short bursts across the seabed. They are carnivores that prey on benthic micro-crustaceans including amphipods, crabs, isopods and shrimp and also polychaete worms and other benthic invertebrates. They dig into the substrate and remain half submerged that they use camouflage and their bony armor plates to avoid predation.

The Pricklebreast Poacher is a resident of Mexican waters of the Pacific but has a limited distribution being found from Magdalena Bay, Baja California Sur, northward along the central and northwest coasts of the Baja Peninsula.

The Pricklebreast Poacher can be confused with the Northern Spearnose Poacher, Agonopsis vulsa (sharp, prominent rostral spine at the tip of the snout; light patch on caudal fin),

From a conservation perspective the Pricklebreast Poacher has not been formally evaluated. They are small in stature, seldom seen by humans, and of limited interest to most.