Barnaclebill Blenny

Barnaclebill Blenny, Hyposoblennius brevipinnis

The Barnaclebill Blenny, Hyposoblennius brevipinnis, whose Spanish common name is borracho vacilón, is a species in the Combtooth Blenny or Blennidae Family, known collectively as borrachos in Mexico. Globally, there are sixteen species in the genus Hyposoblennius, four of which are found in Mexican waters, one in the Atlantic and three in the Pacific. The Barnaclebill Blenny is one of the few species who have migrated through the Panama Canal into the Atlantic.

The Barnaclebill Blennies have shortened elongated bodies with a uniform depth throughout and significant tapering at the rear into the tail. They are dark brown with very subtle colorations including a horizontal row of circular tan patches just below the base of the dorsal fin, a second row of smaller patches or spots just below the first row, and a broad dark band running the length of the body slightly above the mid-line. They are off-white to yellow ventrally. Their head has small brown spots and a prominent oblique band behind the eyes. Their eyes have a dark-edged whitish stripe on their upper and lower margins. The head of breeding males is covered with red spots. Their head is short and robust with a very steep forehead profile. The outermost orbital cirri are unbranched but with one to four shorter cirri at the base. Their mouth is small, opens at the front, and is equipped with one row of teeth with blunt flattened tips on each jaw. Their anal fin has two spines and 14 rays; their caudal fin is rounded; and their dorsal fin has 10 to 12 spines and 15 or 16 rays with a slight notch in between. Their lateral line terminates under the end of the spiny dorsal fin. Their skin is smooth and without scales.

The Barnaclebill Blennies are a coastal species found in the intertidal shallows, bays, and estuaries in rocky areas at depths up to 33 feet. They reach a maximum length of 12.0 cm (4.7 inches). They inhabit empty barnacle shells normally with their heads protruding, for which they are named. They are diurnal, highly territorial predators that feed on floating debris and benthic crustaceans including small crabs. Reproduction is oviparous in distinct pairs with the females depositing eggs in protected areas. The eggs are sticky and adhere to the walls of the shelter; they are then fertilized by the males who guard them for two to three weeks until they hatch. They are a small shallow-water species and very little is known about their behavioral patterns.

In Mexican waters the Barnaclebill Blenny are found from Magdalena Bay southward along the southwest coast of Baja, in the lower two-thirds of the Sea of Cortez, and along the coast of the mainland south to Guatemala.

The Barnaclebill Blenny can be confused with the Bay Blenny, Hypsoblennius gentilis (rows of white blotches on flank) and the Mussel Blenny, Hypsoblennius jenkinsi (mottled brown with row of white spots along sides below mid-line).

The Barnaclebill Blennies are too small to be of interest to most and are normally a “catch-and-release.”

Barnaclebill Blenny, Hypsoblennius brevipinnis. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, August 2011. Length: 4.5 cm (1.8 inches). Identification reconfirmed by Dr. Grant Galland, Scripps Institution of Oceanography, La Jolla, CA.