Porehead Blenny, Labrisomus multiporosus

Porehead Blenny, Labrisomus multiporosus. Fish caught from a coastal tidal pool, Mazatlán, Sinaloa, April 2015. Length: 12.2 cm (4.8 inches). Catch and photograph courtesy of George Brinkman, Guelph, Ontario, Canada.

Porehead Blenny, Labrisomomus multiporosus. Fish caught from coastal waters off Mazatlán, Sinaloa, October 2021. Length: 12.5 cm (4.9 inches). Catch, photograph and identification courtesy of Bart, The Netherlands  (worldangler.eu).

Porehead Blenny, Labrisomus multiporosus. Fish caught within the coastal waters of Magdalena Bay, Baja California Sur, March 2017. Length: 13.1 cm (5.2 inches).

Porehead Blenny, Labrisomomus multiporosus. Fish caught from shore at Km 21, Cabo Real, Baja California Sur, November 2008. Length: 14 cm (5.5 inches).

Porehead Blenny, Labrisomomus multiporosus. Fish caught from within the Puerto Los Cabos Marina, Baja California Sur, April 2022. Length: 14 cm (5.5 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Porehead Blenny, Labrisomus multiporosus. Fish caught within the coastal waters of Magdalena Bay, Baja California Sur, May 2018. Length: 16 cm (6.3 inches).

Porehead Blenny, Labrisomus multiporosus. Underwater photographs taken in Zihuantanejo Bay, Guerrero, March 2018 and February 2023. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Porehead Blenny, Labrisomus multiporosus, whose common Spanish name is trambollo cabeza porosa, is a member of the family Labrisomid Blenny or Labrisomidae Family, and is known in Mexico as trambollo cabeza porosa. Globally, there are twenty-seven species in the genus Labrisomus, of which thirteen are found in Mexican waters, nine in the Atlantic Ocean and four in the Pacific Ocean.

The Porehead Blenny has a elongated robust body with a uniform depth throughout that tapers gradually at the rear into the tail. They are tan to brownish in color with heavy dark brown mottling and irregular bars on their sides. A key to identification is a pair of oblique bands across their cheeks that turn into horizontal lines. They have prominent dark spotting on their caudal, dorsal, and pectoral fins. Their dorsal fin has an ocellus at the front. Their head is broad with a blunt snout, large eyes, a branched cirrus over each eye, and several branched cirri on each side of the nape. Their head is also densely covered with sensory pores after which they are named. Their mouth is large, opens at the front, and is slightly oblique; it is equipped with 1 row of small teeth on the upper and lower jaws and includes teeth on the roof of the mouth. Their anal fin has 2 spines and 17 or 18 rays; their caudal fin is square; and their dorsal fin has 17 to 19 spines and 11 to 13 rays with a deep notch in between. They are covered with small smooth scales.

The Porehead Blenny is a shallow water coastal species found within weed-covered rocky shores at depths up to 20 m (65 feet). They reach a maximum of 18.0 cm (7.1 inches) in length. They are diurnal highly territorial predators that feed mostly on benthic crustaceans including small crabs. Reproduction is oviparous with females depositing eggs in protected areas. The Porehead Blenny 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 Porehead Blenny is a resident of all Mexican waters of the Pacific Ocean with the exception that they are absent from Guerrero Negro, Baja California, northward along the central and northwest coasts of Baja.

The Porehead Blenny can be easily confused with a series of Blennies including the Green Blenny, Labrisomus striatus (brown coloration; brown spots and thin stripes; two oblique bars on cheeks; front dorsal spines are shortest; dark spots on base of anal, caudal, and dorsal fins) and the Largemouth Blenny, Labrisomus xanti (head covered with numerous small white spots).

From a conservation perspective the Porehead Blenny is currently considered to be of Least Concern with stable, widely distributed populations.  They are uncommon and small in stature and of limited interest to most.