Mexican Margarita Blenny, Malacoctenus margarita mexicanus

Mexican Margarita Blenny, Malacoctenus margarita mexicanus, Female. Underwater photograph taken in Zihuantanejo Bay, Guerrero, February 2023. Photograph courtesy of Ron Woheau, Zihuantanejo.

Mexican Margarita Blenny, Malacoctenus margarita mexicanus, Males. Underwater photographs taken in Zihuantanejo Bay, Guerrero, February 2023. Photographs courtesy of Ron Woheau, Zihuantanejo. Identifications courtesy of Dr. Benjamin Victor, Coralreeffish.com.

Mexican Margarita Blenny, Malacoctenus margarita mexicanus, Male and Female. Underwater photographs taken in Zihuantanejo Bay, Guerrero, February 2023. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Mexican Margarita Blenny, Malacoctenus margarita mexicanus, is a member of the Labrisomid Blenny or Labrisomidae Family, and is known in Mexico as trambollo margarita mexicano. Globally, there are twenty-three species in the genus Malacoctenus, of which thirteen are found in Mexican waters, five in the Atlantic and eight in the Pacific Ocean.

The Mexican Margarita Blenny has an elongated body with a uniform depth throughout that tapers gradually at the rear into the tail. They are sexually dimorphic with females being whitish with numerous irregular yellow-brown blotches on the sides, their belly is white, and the gill cover has a large pale edged brown spot. The nuptial males are a dark greenish -gray color with several diffuse dark bars on the sides and 3 black spots on the rear of the back. The head is slender head a pointed snout that has a pair of heavily branched cirri on the nape and a branched cirri over the eyes. Their mouth is large and opens in the front and is equipped with large teeth on the upper jaw. Their anal fin has 2 spines and 20 to 23 rays; their first dorsal fin has 20 to 22 spines; their second dorsal fin has 10 to 12 rays; their pectoral fins have 14 to 16 rays; and their pelvic fins have 3 rays the first of which is one half the length of the third. They have 1 pore on the underside of the head. They have 10 to 12 gill rakers. Their lateral line is visible on the front half of the body, and they are covered with scales.

The Mexican Margarita Blenny is a shallow water benthic coastal species found within coral reefs, rocky reefs and rubble substrate at depths up to 21 m (70 feet). They reach a maximum length of 6.5 cm (2.6 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. The Mexican Margarita 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 Mexican Margarita Blenny is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found within the Sea of Cortez and along the coast of the mainland north of Acapulco; they are absent from the Pacific Coast of Baja.

The Mexican Margarita Blenny is easily confused with the Mexican Blenny, Paraclinus mexicanus (2 to 4 head pores; long third pelvic ray; body with strong markings).

From a conservation perspective the Mexican Margarita Blenny is currently considered to be of Least Concern with stable, widely distributed populations. They are very small in stature, seldom seen by humans and of limited interest to most.