Stripefin Ronquil, Rathbunella alleni
Stripefin Ronquil, Rathbunella alleni, Juvinile. Fish caught from coastal waters off Santa Cruz, California, October 2025. Length: 8.1 cm (3.2 inches). Catch, photograph and identification courtesy of Zachary Fratello, Redondo Beach, California.
Stripefin Ronquil, Rathbunella alleni, Female. Fish caught from coastal waters off Santa Cruz, California, August 2021. Length: 16 cm (6.3 inches). Catch and photograph courtesy of Luke Ovgard, Klamath Falls, Oregon. Identificaiton courtesy of Zachary Fratello, Redondo Beach, California.
Stripefin Ronquil, Rathbunella alleni, Female. Fish caught from coastal waters off Santa Cruz, California, August 2021. Length: 16 cm (6.3 inches). Catch and photograph courtesy of Luke Ovgard, Klamath Falls, Oregon. Identificaiton courtesy of Zachary Fratello, Redondo Beach, California.
Stripefin Ronquil, Rathbunella alleni, Juvinile. Fish caught from coastal waters off Santa Cruz, California, October 2025. Length: 8.1 cm (3.2 inches). Catch, photograph and identification courtesy of Zachary Fratello, Redondo Beach, California.
The Stripefin Ronquil, Rathbunella alleni, is a member of the Bathymasteridae or Ronquil Family, that is also known as the Rough Ronquil and the Stripedfin Ronquil, and in Mexico as ronco pelón aletirrayada and ronco pelón rayado. Globally there are two species in the Genus Rathbunella, both of which three are found in Mexican waters of the Pacific Ocean.
The Stripefin Ronquil has a blenny like body. They are an olive brown to dull red, bluish black or purple color with lighter areas. They have a longitudinal blue stripe that runs the length of the anal fin. The males have several prominent blotches on their sides; the females are relatively pale with darker splotches and spots dorsally with light barring on the lower sides and a blue spot on the anterior of the dorsal fin. They have a long anal fin with 33 rays, that does not have spines and has a uniform height for its entire length, a rounded caudal fin, a dorsal fin that has 46 rays the first five of which are unbranched, no spines, and a uniform height, large and rounded pectoral fins and pelvic fins that are found on the thorax with 1 spine and 5 rays. They are covered with small smooth scales. Their prominent lateral line is high on the body and straight.
The Stripefin Ronquil is a demersal solitary species that is found in shallow exposed coastal waters within rocky structure and substrate on at depths up to 146 m (480 feet). They reach a maximum length of 24.3 cm (9.6 inches). They consume invertebrates including amphipods, copepods, polychaetes, shrimps, and snails. In turn they are preyed upon by a wide variety of fish and Sea Lions. Reproduction is oviparous with batch spawning with external fertilization; each female releases eggs in protected locations among rocks and is guarded by the males. The Bluebanded Ronquil is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, diet, growth, habitat, longevity, movement patterns, and reproduction.
The Stripefin Ronquil is a resident of Mexican waters of the Pacific but has a limited distribution, being found from Bahía San Carlos, Baja California, northward along the northwest coast of Baja.
The Stripefin Ronquil is easily and often confused with the Bluebanded Ronquil, Rathbunella hypoplecta (large in stature; lack canines on the lower jaws). The separation of these two species is exceedingly difficult even for experienced professional ichthyologists. The above identification is based on location of the catch only.
From a conservation perspective the Stripefin Ronquil has not been formally evaluated. They are relatively small in stature and of limited interest to most.