Bigscale Goatfish

Bigscale Goatfish, Pseudupeneus grandisquamis

Bigscale Goatfish, Pseudopeneus grandisquamis, Juvenile. Fish provided by the commercial fishermen of Bahía Kino, Sonora, November 2014. Length: 12 cm (4.7 inches). Photograph 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, California.

Bigscale Goatfish, Pseudupeneus grandisquamis. Fish caught from coastal waters off Puerto Los Cabos, Baja California Sur, October 2007. Length: 15 cm (5.9 inches).

Bigscale Goatfish, Pseudupeneus grandisquamis. Underwater photographs taken in Zihuantanejo Bay, Guerrero, March 2018. Photographs courtesy of Ron Woheau, Zihuantanejo.

The Bigscale Goatfish, Pseudupeneus grandisquamis, is a member of the Goatfish or Mullidae Family, and is known in Mexico as chivo escamudo. Globally, there are four species in the genus Pseudupeneus, of which two are found in Mexican waters, one in the Atlantic and one in the Pacific Ocean.

The Bigscale Goatfish has an elongated compressed body that has a depth that is 30% to 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. Their head has a pointed snout, eyes set high on the head, a small protrusible mouth with small villiform or conical teeth, and 2 long barbels on their chin, which allow for easy identification. Their anal fin has 2 spines and 6 rays; their caudal fin is deeply forked; their first dorsal fin has 7 or 8 spines; their second dorsal fin has 1 spine and 8 rays; their pectoral fins have 13 to 16 rays. rays; and their pelvic fins and large and located just before the pectoral fin base. They are covered with large rough scales.

The Bigscale Goatfish inhabits sandy and muddy bottoms from the intertidal zone to depths up to 67 m (220 feet). They reach a maximum of 30 cm (11.8 inches) in length. 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 co mingling 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. Bigscale Goatfish are pelagic spawners releasing buoyant eggs that travel the currents for several days until hatching. The Bigscale Goatfish 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 Bigscale Goatfish is a resident of all Mexican waters of the Pacific Ocean.

The Bigscale Goatfish is easy to identify being one of only three Goatfish found in Mexican waters of the Pacific Ocean. It is significantly different in both color and body shape from the Mexican Goatfish, Mulloidichthys dentatus and the Yellowfin Goatfish, Mulloidichthys vanicolensis, both of which is normally found in shallow in-shore waters.

From a conservation perspective the Bigscale Goatfish is currently considered to be of Least Concern, with stable, widely distributed populations. They are exceedingly rare in the greater Los Cabos area. The fish pictured below is the only one I have seen in twenty years of fishing in the greater Los Cabos area. They are reported to be a by-catch of deep water trawlers.