Mexican Night Sergeant, Abudefduf declivifrons

Mexican Night Sergeant, Abudefduf declivifrons, Juveniles. Underwater photographs taken from coastal waters off Huatulco, March 2021. Photographs courtesy of Marina Sutormina, Stockholm, Sweden. Identification courtesy of Dr. Ross Robertson, Smithsonian Tropical Research Institute, Panama.

Mexican Night Sergeant, Abudefduf declivifrons, Juvenile. Fish caught from shore at Las Frailes, Baja California Sur, March 2022. Length: 6.1 cm (2.4 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore at Mazatlán, Sinaloa, April 2015. Length: 10.0 cm (3.9 inches). Catch and photograph courtesy of George Brinkman, Guelph, Ontario, Canada.

Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore at Km 21, Cabo Real, Baja California Sur, April 2018. Length: 10.0 cm (3.9 inches). Fish caught from two-foot water in the “suds” and was virtually invisible. An interesting color adaptation to avoid becoming prey from the marauding needlefish.

Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore in Mazatlán, Sinaloa, April 2015. Length: 10.7 cm (4.2 inches). Catch and photograph courtesy of Michael Verdirame, Markham, Ontario, Canada.

Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from coastal waters off Mazatlán, Sinaloa, October 2021. Length: 10.7 cm (4.2 inches). Catch, photograph and identification courtesy of Bart, The Netherlands  (worldangler.eu).

Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore in Mazatlán, Sinaloa, April 2015. Length: 10.7 cm (4.2 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.

Mexican Night Sergeant, Abudefduf declivifrons.Fish caught from shore at Las Frailes, Baja California Sur, March 2022. Length: 6.1 cm (2.4 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore at Km 21, Cabo Real, Baja California Sur, May 2003. Length: 18.0 cm (7.1 inches). Second and third photographs taken one hour after collection.

Mexican Night Sergeant, Abudefduf declivifrons. Underwater photograph taken in the greater Cabo San Lucas area, Baja California Sur, November 2017. Length: ca. 12 cm (4.7 inches).

Mexican Night Sergeant, Abudefduf declivifrons. Underwater photographs taken in Zihuantanejo Bay, Guerrero, March 2019. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Mexican Night Sergeant, Abudefduf declivifrons, is a member of the Damselfish or Pomacentridae Family, and is known in Mexico as petaca Mexicana. Globally, there are twenty-five species in the genus Abudefduf, of which four are found in Mexican waters, two in the Atlantic and two in the Pacific Ocean.

The Mexican Night Sergeant has a relatively deep oblong compressed body, with a depth that is 53% to 57% of standard length, thus similar in nature to freshwater bluegills. They are gray-brown in color with four or five very subtle narrow white bars that fade with maturity and a black blotch at the base of their pectoral fins. Their scales have dark borders. Their head has a steep profile and a small protrusible mouth that has prominent white wide lips and a single row of teeth. Their caudal fin is forked with broad lobes. They have 2 anal spines and 10 anal rays and a continuous dorsal fin with 13 spines and 12 or 13 rays. They have 19 to 23 gill rakers. Their lateral line is incomplete and ends under the edge of their dorsal fin base. Their body is covered with rough scales.

The Mexican Night Sergeant is a non-migratory species found in shallow water over and within rocky reef structure buffeted by wave action at depths up to 20 feet. They reach a maximum length of 19.5 cm (7.7 inches), established by one of my personal catches. They are diurnal feeders consuming primarily algae, benthic invertebrates and plankton. Reproduction is oviparous with pairing of individuals; eggs are distributed demersal and adhere to the substrate due to their stickiness. Males guard and aerate the eggs. The Mexican Night Sergeant 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 Mexican Night Sergeant is a resident of Mexican waters of the Pacific Ocean but has a limited distribution ranging from Magdalena Bay, Baja California Sur, southward along the southwest coast of Baja, in the southern two-thirds of the Sea of Cortez, and along the coast of the mainland south to Guatemala.

The Mexican Night Sergeant cannot be easily confused with any other species due to its coloration and body shape, however, it is virtually identical to the Night Sergeant, Abudefduf taurus (found only in the Atlantic Ocean).

From a conservation perspective the Mexican Night Sergeant is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature but are considered an excellent food fish. They are classic nibblers, thus difficult to catch by hook and line.