Bigscale Goatfish, Pseudupeneus grandisquamis
The Bigscale Goatfish, Pseudupeneus grandisquamis, whose common Spanish name is chivo escamudo, is a species in Goatfish or Mullidae Family, known collectively as chivos in Mexico. Globally, there are only four species in the genus Pseudupeneus, two of which are found in Mexican waters, one in the Atlantic and one in the Pacific.
The Bigscale Goatfish have elongated compressed bodies that have depths that are 30 – 34% of standard length. The undersides of their head and body are nearly flat. They are reddish brown to violet in overall color and taper to reddish pink and whitish ventrally. They have a black blotch under the rear of their dorsal fin and numerous pearly white spots on their head, which are organized in three narrow stripes along the upper side of the body and run from the tip of the snout to the caudal fin. Their forked caudal fin is a pinkish red. They have a pointed snout and eyes that are set high on the head. They feature a small protrusible mouth with small villiform or conical teeth and two long barbels on their chin, which allow for easy identification. They have two widely spaced dorsal fins, the first with seven or eight spines and the second with one spine and eight soft rays. They have large pelvic fins located just before the pectoral fin base. They are covered with large rough scales.
The Bigscale Goatfish inhabit sandy and muddy bottoms from the intertidal zone to depths up to 220 feet. They reach a maximum length of 30 cm (11.8 inches). Their barbels have sensory organs utilized for finding food, which consists mainly of small bottom-living animals such as crustaceans, mollusks, worms, and other small invertebrates. During the day, they form large non-feeding schools comingling with other species. At night, they feed as individuals. Males also use their barbels to attract females during courtship. When not in use, the barbels are tucked tightly under the chin. Goatfish are pelagic spawners releasing buoyant eggs that travel the currents for several days until hatching.
In Mexican waters the Bigscale Goatfish are found in all waters of the Pacific.
The Bigscale Goatfish is easy to identify being one of only two Goatfish found in Mexican waters of the Pacific. It is significantly different in both color and body shape from the Mexican Goatfish, Mulloidichthys dentatus, which is normally found in shallow in-shore waters.
The Bigscale Goatfish are exceedingly rare in the greater Los Cabos area. The fish pictured below is the only one I have seen in 20 years of fishing in the greater Los Cabos area. They are reported to be a by-catch of deep water trawlers.
Bigscale Goatfish, Pseudopeneus grandisquamis, juvenile. Fish provided by the commercial fishermen of Bahía Kino, Sonora, November 2014. Length: 12 cm (4.7 inches). Photo courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora. Identification reconfirmed by H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, CA.