Rosy Blenny, Malacoctenus macropus
Rosy Blenny, Malacoctenus Macropus, Female. Fish caught from coastal waters off Ft. Lauderdale, Florida, February 2022. Length: 3.8 cm (1.5 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
Rosy Blenny, Malacoctenus Macropus, Female. Underwater photography taken within the coastal interway of Ft. Lauderdale, Florida, September 2021. Photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
The Rosy Blenny, Malacoctenus macropus, is a member of the Labrisomid Blenny or Labrisomidae Family, that are also known as the Rose Blenny and the Scaly Blenny and in Mexico as trambollo rosado. 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 Rosy Blenny has an elongated body with a uniform depth throughout that tapers gradually at the rear into the tail. They are sexually dimorphic with the males being larger and have a larger head and a longer dorsal fin than the females. The males have gray stripes and white spots along the upper third of the body and red coloration on the sides and under the head. The females are tan in color with asymmetrical bars on the sides and are uniformly covered with small white spots. Their anal fin has 2 spines and 20 or 21 rays, their first dorsal fin has 21 or 22 spines, their second dorsal fin has 8 to 11 rays, their pectoral fins have 15 rays, and their pelvic fins have 1 spine and 3 rays and are found before the pectoral fins. Their head has a small, pointed, flattened snout with a small mouth that opens in the front with fleshy lips, outer canine teeth and small inner teeth. They have one simple cirrus over the nostril, a long simple cirrus over the eyes, and pair of cirri on each side of the nape. They are covered with ctenoid scales.
The Rosy Blenny is a shallow water demersal species that is found within reefs and rubble habitats that have an abundance of algae and in mangrove groves. They are common in sponge beds and seagrass beds within estuaries. They are found at depths up to 8 m (26 feet). They reach a maximum of 5.2 cm (2.0 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. Underwater they can be seen as single individuals perched on top of the substrate relying on camouflage to avoid predation. The Rosy 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 Rosy Blenny is a resident of Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the Caribbean with the exception that they are absent from the extreme northwestern Gulf of Mexico, from the Texas border south to Tuxpan, Veracruz.
The Rosy 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 (ocelli spot under the rear dorsal spines) and the Saddled Blenny, Malacoctenus triangulates (four triangular bars on upper back).
From a conservation perspective The Rosy 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. They are utilized by the aquarium trade on a limited basis. Their long-term survival is threatened by water pollution and habitat degradation.