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Ray-finned Fishes of Zihuatanejo

CLASS ACTINOPTERYGII

-Animals (Kingdom Animalia)

-Chordates (Phylum Chordata)

-Vertebrates (Subphylum Vertebrata)

-Ray-finned Fishes (Class Actinopterygii)

-Butterflyfishes, Angelfishes, and Allies (Order Acanthuriformes)

-Grunts (Family Haemulidae)

-Subfamily Haemulinae

-Genus Anisotremus

-Silver Gray Grunt (Anisotremus caesius)


The Silver Gray Grunt, also known as Burro Mojarro, is a coastal marine fish recognized by its deep, laterally compressed body, silvery-gray coloration, and subtle bronze or yellowish hues along the sides. It belongs to the grunt family (Haemulidae), named for the audible grunting sounds it produces by grinding its pharyngeal teeth, often when handled or stressed. This species typically inhabits shallow coastal waters, including sandy bottoms, seagrass beds, rocky areas, and reefs, where juveniles often seek shelter in estuaries and lagoons. Primarily nocturnal, the Silver Gray Grunt feeds on small benthic invertebrates such as crustaceans, worms, and mollusks.

Diet

  • Carnivorous, demersal feeder that takes small benthic invertebrates.

  • Its diet includes mobile crustaceans, small gastropods and bivalves, and benthic worms.

  • It is primarily a nocturnal predator, foraging over hard reef and rubble substrates.

Range

  • Tropical eastern Pacific, ranging from southern Sinaloa, Mexico, southward to Colombia and including Cocos Island, Costa Rica.

  • It occurs along the Mexican Pacific coast, including Michoacán and Guerrero.

  • It is present in Zihuatanejo Bay, including juvenile fish photographed in the bay.

Habitat

  • Primarily a bottom-dwelling species associated with rocky reefs, hard bottoms, and rubble.

  • Usually occurs in shallow coastal water from approximately 3–25 metres.

  • It is generally associated with reef structure during the day and forages over the bottom at night.

Description

  • Medium-sized grunt with a deep, strongly compressed body and a high back.

  • Head is short and blunt, with a small, low-set mouth and thick, fleshy lips.

  • Body is golden-grey or yellowish, becoming paler or whitish on the lower sides.

  • A broad, dark bar occurs immediately behind the head; this marking is particularly conspicuous in juveniles.

  • Fins are generally yellowish to dusky, and large adults may have a dark blotch at the base of the caudal fin.

  • Pectoral fins are relatively long, reaching to or slightly beyond the origin of the anal fin.

  • Grows to approximately 30 cm in total length.

Silver Gray Grunt

Anisotremus caesius

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