Bay Blenny

Bay Blenny, Hyposoblennius gentilis

The Bay Blenny, Hyposoblennius gentilis, whose Spanish common name is borracho de bahia, 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 Bay Blennies have elongated bodies that are deepest under the front part of the dorsal fin and taper gradually to the tail. They are overall dark brown with green tints and are white on their throat and belly regions. Their upper back has a series of dark brown saddle-like marks and their sides have a row of off-white blotches along the mid-body. Their dorsal fin has a red spot at the front. Adult males have a red bar across their throat that becomes more pronounced during breeding season. Adult females have a large metallic blue spot between their first and third dorsal spines. Their head is short and robust with a very steep forehead profile and small cirri above the posterior nostril; the cirri in males are exceedingly long. 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 16 to 19 rays; their caudal fin is rounded; and their dorsal fin has 11 or 12 spines and sixteen to 18 rays with a slight notch in between.

The Bay Blennies are a coastal species found in the intertidal shallows, bays, and estuaries at depths up to 80 feet. They reach a maximum length of 14.7 cm (5.8 inches). They feed on algae and small benthic invertebrates. 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. Each female will spawn three or four times per year. They are eurythermal and thus able to tolerate extreme winter and summer temperatures.  They are reported to have a lifespan of up to seven years. They are a small shallow-water species and very little is known about their behavioral patterns.

In Mexican waters the Bay Blennies are found along the west coast of Baja and throughout the Sea of Cortez. They are absent from along the coast of the mainland south to Guatemala. The Bay Blenny is the most common Combtooth Blenny in the upper Gulf.

The Bay Blenny is easily confused with three other blennies, the Barnaclebill Blenny, Hypsoblennius brevipinnis (white and black spots on throat), the Mussel Blenny, Hypsoblennius jenkinsi (mottled brown and white body color), and the Notchfin Blenny, Entomacrodus chiostictus (deep notch between dorsal fins).

The Bay Blennies are too small to be of interest to most and are normally a “catch-and-release.” They are used on a limited basis in the aquarium trade and thrive in captivity.

Bay Blenny (1)

Bay Blenny, Hyposoblennius gentilis, Female. Fish provided by the commercial bait salesmen of Puerto Los Cabos Marina, March 2014. Length: 5.2 cm (2.0 inches). Identification courtesy of Dr. Phil Hastings, Scripps Institution of Oceanography, La Jolla, CA.

Bay Blenny, Hyposoblennius gentilis, Male Underwater photo taken in coastal waters with Mission Bay, San Diego, CA, September 2017. Length: 12.7 cm (5.0 inches). Photo courtesy of Bob Hillis, Ivins, UT.