Largemouth Blenny

Largemouth Blenny, Labrisomus xanti

The Largemouth Blenny, Labrisomus xanti, whose common Spanish name is chalapo, is a species in the Labrisomid Blenny or Labrisomidae Family, known collectively as trambollos in Mexico. Globally, there are twenty-seven species in the genus Labrisomus, of which thirteen are found in Mexican waters, nine in the Atlantic and four in the Pacific.

The Largemouth Blennies have shortened elongated robust bodies with a uniform depth throughout that tapers gradually at the rear into the tail. They are greenish-brown in color with eight dark bars along their sides and two thin dark stripes bordering a pale area behind and a little below their eyes. They have a black blotch at the front of their dorsal fin and numerous small white spots on the lower parts of their head and body. Breeding males are red with a large black spot between the second and fourth dorsal spines (pictured below). 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 mouth is large, opens at the front, and is slightly oblique; it is equipped with one row of small teeth on the upper and lower jaws and includes teeth on the roof of the mouth. Their anal fin has two spines and 17 to 19 rays; their caudal fin is square; and their dorsal fin has 17 to 19 spines and 10 to 12 rays with a deep notch in between. They are covered with small smooth scales.

The Largemouth Blennies are a shallow water coastal species found within weed-covered rocky shores at depths up to 35 feet. They reach a maximum length of 18.0 cm (7.1 inches). 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.  Very little is known about their behavioral patterns.

In Mexico the Largemouth Blenny are found from Guerrero Negro southward along central and southwest coasts of Baja, throughout the Sea of Cortez, and along the coast of the mainland north of Acapulco.

The Largemouth 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 Porehead Blenny, Labrisomus multiporosus (two oblique bars on cheeks; rows of spots on fins).

Although plentiful, the Largemouth Blennies are of limited interest to most, due to their small size.

Largemouth Blenny, Labrisomus xanti. Fish caught from shore at Km 21, Cabo Real, Baja California Sur, April 2003. Length: 9.1 cm (3.6 inches). Fish identification courtesy of Dr. Ross Robertson, Smithsonian Tropical Research Institute, Panama.


Largemouth Blenny, Labrisomus xanti. Fish caught out from shore at  La Bocana, Baja California Sur, October 2015. Length: 12.7 cm (5.0 inches). Catch and photo courtesy of George Brinkman, Guelph, Ontario, Canada.

Largemouth Blenny, Labrisomus xanti. Fish caught with Jimmy Camacho, Jimmy’s Sportfishing, Puerto Adolfo Lopez Mateos, Baja California Sur, (, 613-114-0761; 612-204-1960) within the coastal waters of Magdalena Bay, Baja California Sur, March 2017. Length: 13.1 cm (5.2 inches).

Largemouth Blenny (2)

Largemouth Blenny, Labrisomus xanti, breeding male. Fish caught from shore at  Cero Colorado, Baja California Sur, March 2015. Length: 15.3 cm (6.0 inches). Fish identification courtesy of Dr. Phil Hastings, Scripps Institution of Oceanography, La Jolla, CA.

Largemouth Blenny, Labrisomus xanti, breeding male. Underwater photo taken in coastal waters off La Jolla, CA, August 2016. Length: 15.2 cm (6.0 inches). Photo and identification courtesy of Bob Hillis, Ivins, UT.