Island Kelpfish, Alloclinus holderi

Island Kelpfish, Alloclinus holderi. Underwater photograph taken in coastal waters of Catalina Island, California, July 2019. Photograph courtesy of Bob Hillis, Ivins, Utah.

The Island Kelpfish, Alloclinus holderi, is a member of the Labrisomid Blenny or Labrisomidae Family, and is known in Mexico as trambollos isleño. It was named in honor of Charles Frederick Holder, an American naturalist, conservationist, and writer who founded the Tuna Club of Avalon. Globally, this is the only species in the genus Alloclinus, and it is found in Mexican waters of the Pacific Ocean.

The Island Kelpfish has an elongated body with long and dorsal fin bases. Their head has a 3-pronged cirrus above each eye and a short snout. They are barred, and striped in shades of red to maroon, lavender, orange and tan with small white to pale spots covering the body and bright orange fins. They have a series of dark blotches along the centers of the sides. Most fish have very thin striping of various colors. They have the ability to change colors to match their backgrounds to avoid predation. Keys to identification include the first dorsal is the same height at the second dorsal, evenly spaced elevated second dorsal rays, and pale round blotch that extends from the lower corner of the eye onto the cheek. Their anal fin has 2 spines and 21 to 23 rays, their first dorsal fin has 24 to 26 spines and their second dorsal fin has 9 to 11 rays; their pectoral fins have 13 or 14 spines; and, their pelvic fins have 1 spine and 3 rays. They have 4 to 9 gill rakers.

The Island Kelpfish is a shallow water demersal coastal species found within rocky areas at depths up to 91 m (298 feet). They reach a maximum length of 11.5 cm (4.5 inches). They are solitary individuals and take shelter at night. They are diurnal territorial predators that feed on benthic crustaceans. Reproduction is oviparous with each female depositing 200 to 1,400 eggs in protected areas.  They are known to provide cleaning services to various fish including the Giant Sea Bass. The Island Kelpfish 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 Island Kelpfish is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found from Isla Asuncion (Guerrero Negro area), Baja California Sur northward along the central and northwest coasts of Baja.

The Island Kelpfish is a straightforward identification that is not easily confused with any other Labrisomid Blenny due to its unique coloration pattern.

From a conservation perspective the Island Kelpfish is currently considered to be of Least Concern with stable, widely distributed populations. In some locations they are exceedingly common, however, they are exceedingly small in stature and of limited value to most.