Mexican Night Sergeant, Abudefduf declivifrons
The Mexican Night Sergeant, Abudefduf declivifrons, whose common Spanish name is petaca Mexicana, is a species in the Damselfish or Pomacentridae Family, known collectively as castañetas and jaquetas in Mexico. Globally, there are twenty-five species in the genus Abudefduf, four of which are found in Mexican waters, two in the Atlantic and two in the Pacific.
The Mexican Night Sergeants have relatively deep oblong compressed bodies, with a depth that is 53 – 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 two 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 Sergeants are 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, plankton, and benthic invertebrates. 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.
In Mexican waters the Mexican Night Sergeant are found from Magdalena Bay 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, due to its coloration and body shape cannot easily be confused with any other species, however, it is virtually identical to the Night Sergeant, Abudefduf taurus (found only in the Atlantic Ocean).
The Mexican Night Sergeants are rather small but are considered an excellent food fish. They are classic nibblers, thus difficult to catch by hook and line.
Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore at Km 21, Cabo Real, Baja California Sur, May 2003. Length: 8.0 cm (3.1 inches). Second and third photos taken one hour after collection.
Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore at Mazatlán, Sinaloa, April 2015. Length: 10.0 cm (4.9 inches). Catch and photo courtesy of George Brinkman, Guelph, Ontario, Canada.
Mexican Night Sergeant, Abudefduf declivifrons. Fish caught from shore in Mazatlán, Sinaloa, April 2015. Length: 10.7 cm (4.2 inches). Catch and photo courtesy of Michael Verdirame, Markham, Ontario, Canada.