Rivulated Mutton Hamlet, Alphestes multiguttatus

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught from coastal waters off Mazatlán, Sinaloa, October 2020. Length: 10 cm (3.9 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught from coastal waters off Islamorada, Florida, April 2012. Length: 16 cm (6.3 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught off Point Palmilla, Baja California Sur, April 2010. Length: 21 cm (8.3 inches).

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught from coastal waters off Mazatlán, Sinaloa, October 2021. Length: 22 cm (8.7 inches). Catch, photograph and identification courtesy of Bart, The Netherlands  (worldangler.eu).

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught from coastal waters off Puerto Vallarta, Jalisco, February 2023. Length: 24 cm (9.4 inches). Catch and photograph courtesy of Ben Cantrell, Peoria, Illinois.

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught from coastal waters off Point Palmilla, Baja California Sur, June 2019. Length: 23 cm (9.1 inches).

Rivulated Mutton Hamlet, Alphestes multiguttatus. Fish caught from coastal waters off Puerto Chomes, Costa Rica, March 2021. Length: 30 cm (12 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Rivulated Mutton Hamlet, Alphestes multiguttatus, and Pacific Mutton Hamlet, Alphestes immaculatus, pectoral fin comparisons. Fish of similar length provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, December 2014.

The Rivulated Mutton Hamlet, Alphestes multiguttatus, is a member of the Sea Bass or Serranidae Family, and is known in Mexico as guaseta rayada. Globally, there are three species in the genus Alphestes, and all three are found in Mexican waters, one in the Atlantic Ocean and two in the Pacific Ocean.

The Rivulated Mutton Hamlet has a deep, strongly compressed body with a depth that is less than the head length and 32% to 37% of standard length. They have a rusty brown appearance with darker brown blotches forming irregular bars on their sides. They have large eyes and a short snout. Their pectoral fins have 5 or 6 regularly aligned transverse bars, a key to identification. Their anal fin has 2 spines and 9 rays, their caudal fin is rounded; their dorsal fin has 11 spines and 18 to 20 rays; and, their pectoral fins have 17 to 19 rays.  They have 6 to 8 gill rakers on the upper limb and 14 to 16 gill rakers on the lower limb. They are covered with smooth scales.

The Rivulated Mutton Hamlet is a non-migratory shallow water species found at depths up to 30 m (100 feet). They reach a maximum of 30 cm (12 inches) in length. They are found hiding in rocky crevices, seagrass weed patches or partially covered with sand during the day and become active predators at night. They feed primarily on benthic crustaceans and rely on camouflage to escape detection. The Rivulated Mutton Hamlet 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 Rivulated Mutton Hamlet is a resident of Mexican waters of the Pacific Ocean but have a limited distribution being found from Magdalena Bay, Baja California Sur, southward along the southwest coast of Baja, in the southern two-thirds of the Sea of Cortez along the east coast of the Baja, and along the coast of the mainland south to Guatemala.

The Rivulated Mutton Hamlet is easy to identify, although it is similar and almost identical to the Pacific Mutton Hamlet, Alphestes immaculatus (mottled brown spots along its sides; caudal fin heavily spotted; body width 36% to 43% of standard length).

From a conservation perspective the Rivulated Mutton Hamlet is currently considered to be of Least Concern with stable, widely distributed populations. They are too small to be of interest to most and upon release they will immediately attract and be consumed by seabirds since they seldom are able to return to the deep on their own.