Blackeye Goby, Rhinogobios nicholsii

Blackeye Goby, Rhinogobios nicholsii. Fish caught from within Monterey Bay, Monterey, California, August 2021. Length: 6.5 cm (2.6 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Blackeye Goby, Rhinogobios nicholsii. Fish caught from within Monterey Bay, Monterey, California, August 2021. Length: 8.1 cm (3.2 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Blackeye Goby, Rhinogobios nicholsii. Fish caught from a pier in Port Alberni, British Columbia, August 2021. Length: 9.6 cm (3.8 inches). Catch, photograph and identification courtesy of of George Brinkman, Guelph, Ontario, Canada.

Blackeye Goby, Rhinogobios nicholsii. Fish caught from coastal waters off Seattle, Washington, July 2018. Length: 10.2 cm (4.0 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Blackeye Goby, Rhinogobios nicholsii. Fish caught from coastal waters off San Diego, California, October 2020. Length: 11.5 cm (4.5 inches). Catch, photograph and identification courtesy of Ben Cantrell, San Diego, California.

Blackeye Goby, Rhinogobios nicholsii. Underwater photographs taken in coastal waters off Catalina Island, California, July 2019. Photographs and identification courtesy of Bob Hillis, Ivins, Utah.

The Blackeye Goby, Rhinogobios nicholsii, is a member of the Goby or Gobiidae Family, and is  known in Mexico as gobio triste. The fish is named for its eyes and after Captain H.E. Nichols of the United States Navy who discovered the species. Globally, there are sixty-six species in the genus Rhinogobios, of which one, this species, is found in Mexican waters of the Pacific Ocean.

The Blackeye Goby has an elongated robust body with a round cross section. They are a very pale tan to olive with brown or green mottling and speckles. Their head has a rounded snout, large black eyes, a distinct iridescent blue spot under each eye, the margins of the first 5 spines of the dorsal fin are black, and breeding males have a black pelvic disk. Their anal fin has 11 or 12 rays; their caudal fin is round; their first dorsal fin has 5 to 7 spines; their second dorsal fin has 12 to 14 rays and a long base; and their pelvic fins are long and reach the anus and form a ventral sucking disc. The body is covered with large cycloid scales.

The Blackeye Goby is a small demersal species this is found in bays over sandy and rocky substrate, exposed rocky shore, kelp forests and protected rocky shores and protected sandy beaches from the intertidal zone to depths up to 140 m (459 feet). They prefer quiet protected areas with access to rocks or holes to which they can retreat. They utilize color for protection to avoid predation and are able to blend into the background. Juveniles are found off-shore among plankton. They reach a maximum of 15 cm (4.6 inches) in length. They are active daytime predators, staying close to shelter, that feed on mollusks, such as limpets and snails and the crustaceans (amphipods, copepods and shrimp). In turn they are preyed upon by Albacore, Thunnus alalonga, various rockfishes, and various birds including Brandt’s Cormorant, Phalacrocorax penicillatus, the Double-crested Cormorant, Phalacrocorax auratus, and the Pelagic Cormorant, Phalacrocorax pelagicus. At night they take shelter. Reproduction is oviparous with spawning occurring over several months. Males are known to collect permanent harem groups composed of several smaller females. Each female deposit 3,300 to 4,800-minute pink eggs that are then fertilized and guarded by the males for several weeks by the males. Their larvae are pelagic and float on the ocean surface. They are a monandric protogynous hermaphrodites with the fish being born female and then mid-life change to males. They have life spans of five years. The Blackeye Goby 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 Blackeye Goby can be confused with the Bay Goby, Lepidogobius lepidus (does not have black eyes), and the Northern Ronquil, Ronquilus jordani (has a single dorsal fin).

The Blackeye Goby is a resident of Mexican waters of the Pacific but has a limited distribution being found from Punta Rompiente (Guerrero Negro), Baja California Sur northward along the central and northwest coasts of Baja.

From a conservation perspective the Blackeye Goby has not been formally evaluated. They are a common by-catch by pier and shore perch fisherman along the entire coast of California but are exceedingly small in stature and of limited value to most. They are utilized by the aquarium trade and can be found in public aquariums.