Seaweed Blenny, Parablennius marmoreus
Seaweed Blenny, Parablennius marmoreus. Fish caught from coastal waters off Broward County, Florida, June 2021. Length: 10.8 cm (4.3 inches). Catch, photograph and identification courtesy of Ben Cantrell, Sebastian, Florida.
The Seaweed Blenny, Parablennius marmoreus, is a member of the Combtooth Blenny or Blennidae Family, and is known in Mexico as blenio marmoreo and borracho marmóreo. Globally, there are twenty-five species in the genus Parablennius, of which one, this species, is found in Mexican waters of the Atlantic Ocean.
The Seaweed Blenny has an elongated compressed body. They vary in color with some fish being entirely yellow while others are pale tan, red-brown or orangish with thin blue bars radiating down from the eyes, orange spots on the head and brown spots on the side that might be clustered into rows with the central row forming a broad stripe that runs from the head to the tail. Some fish are white with a black stripe along the top of the back on the front two-thirds of the body and another along the upper side that extends through each eye. The ventral surface is white. They have the ability to change colors to match the back of their background. They have an ocellus at the front of the dorsal fin. Their head has blunt snout and has a cirrus with several branches over each eye with jaws set in single rows with blunt points and a canine tooth at the rear of top and bottom jaws; the canines are larger in males. Their anal fin has 2 spines and 17 or 18 rays; their caudal is broadly rounded; their first dorsal fin has 12 spines; their second dorsal fin has 17 to 18 rays; and, their pectoral fins have 14 rays. Their lateral line is short and ends under the dorsal fins. They do not have scales.
The Seaweed Blenny is a non-migratory coastal demersal species that is found in shallow water on rocky, weedy reefs. The juveniles are known to associate with Sargassum, at depths up to 35 m (115 feet). They reach a maximum length of 10.8 cm (4.3 inches). The males are highly territorial and will vigorously defend their habitat against intruders. They are known to inhabit empty tube-worm shells and to extend their heads from the opening. They are diurnal omnivores that primarily consume algae and limited amounts of crustaceans, hydroids and polychaetas. In turn they are preyed upon by large crustaceans including crabs and lobsters and larger demersal fish. Reproduction is oviparous in distinct pairs with adhesive demersal eggs and attach to empty bivalve shells, holes and crevices in rocks, sponges, and inside discarded marine debris the substrate via filamentous, adhesive pads that are guarded by the males and then turn into planktonic larvae. The Seaweed Blenny is a small shallow-water species that 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 Seaweed Blenny is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.
The Seaweed Blenny has unique tuffs of branched cirri above each eye and makes it a straightforward identification. However, it is similar to the Atlantic Mangrove Blenny, Lupinoblennius vinctus (dark brown body), the Highfin Blenny, Lupinoblennius nicholsi, (simple cirrus over the eyes; colored ventral area); the Molly Miller, Scartella cristata (row of comb-like cirri down the central portion of the head anterior to the dorsal fin; olive brown with dark markings, barred caudal fin) and the Pearl Blenny, Entomacrodus nigricans (simple cirri over the eyes; notch between the dorsal fins, low, straight edged first dorsal fin.
From a conservation perspective the Seaweed Blenny is currently considered to be of Least Concern with stable, widely distributed populations. They are too small in stature to be of interest to most. They are utilized by the aquarium trade on at a modest level.