Dusky Blenny, Malacoctenus gilli
Dusky Blenny, Malacoctenus gilli. Fish caught from coastal waters off Noord, Aruba, February 2023. Length: 6.4 cm (2.5 inches). Catch, photograph, and identification courtesy of James Lafontaine, Long Island, New York.
The Dusky Blenny, Malacoctenus gilli, is a member of the Labrisomid Blenny or Labrisomidae Family, that is known in Mexico as sapito pardo and trambollo pardo. Globally, there are eighteen species in the genus Malacoctenus, of which fourteen are found in Mexican waters, six in the Atlantic and eight in the Pacific Ocean.
The Dusky Blenny has an elongated body with a uniform depth throughout that tapers gradually at the rear into the tail. They are light to dark gray in color that transitions to pale ventrally. The scales have dark edges and whitish centers. The body has indistinct dark bars that extend onto the dorsal fin. They have a prominent dark semi-ocullus at the front of the dorsal fin and a dark ocellus on the upper body that extends onto the last dorsal spines, keys to identification. Their anal fin has 2 spines and 19 or 20 rays, their first dorsal fin has 19 or 20 spines, their second dorsal fin has 9 to 11 rays, their pectoral fins have 14 rays, and their pelvic fins have 1 spine and 3 ray and is inserted before the pectoral fins. Their head is slender with a pointed snout that is slightly flattened with one simple cirrus over the nostril, a long, forked cirrus over the eyes and three to seven branched cirri on each side of the nape. The lateral line is found in the first half of the body and the rear half is covered with scales.
The Dusky Blenny is a shallow water demersal species that is found within sandy bottoms with rocks or boulders, seagrass beds, and patch reefs. They are found at depths up to 5 m (8 feet). They reach a maximum of 7.6 cm (3.0 inches) in length. They are carnivores that feed on crustaceans and benthic worms. Reproduction is oviparous with each female laying eggs in nests placed in cracks and holes within the reef that are then fertilized by the males. The males actively care for and protect the nests from predations. Their larvae pass through numerous developmental stages before becoming adults. They rely on being cryptically colored and remaining close to shelter to help avoid predation. They are known to associate with Condylactis Sea Anemones. They are known to be preyed upon by the Western Atlantic Trumpetfish, Aulostomus maculatus and their juveniles by the highly invasive, recently introduced, Red Lionfish, Pterois volitans. The Dusky 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 Dusky Blenny is a resident of Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the Caribbean. In the Gulf of Mexico they are limited to a small coastal stretch in southern Veracruz. In the Caribbean they are found in all Mexican waters along the East Coast of the Yucatán Peninsula south to Belize.
The Dusky Blenny is most likely confused with the Barfin Blenny, Malacoctenus versicolor (five wide dark bars that extend into the dorsal fin), the Dusky Blenny, Malacoctenus gilli (ocelli spots at the front and rear of the first dorsal fin), the Goldline Blenny, Malacoctenus aurolineatus (lower body covered with thin gold stripes), the Imitator Blenny, Malacoctenus erdmani (lower body with dark lines), the Rosy Blenny, Malacoctenus macropus (coved with numerous white spots) and the Saddled Blenny, Malacoctenus triangulates (four triangular bars on upper back).
From a conservation perspective the Dusky Blenny is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature and of limited interest to most. Their long-term survival is threatened by water pollution and habitat degradation.