Ray-finned Fishes of Zihuatanejo

CLASS ACTINOPTERYGII

-Blennies (Order Blenniiformes)

-Pike-Blennies, Tube-Blennies, and Flagblennies (Family Chaenopsidae)

-Genus Acanthemblemaria

-Mexican Barnacle Blenny (Acanthemblemaria macrospilus)

The Mexican Barnacle Blenny (Acanthemblemaria macrospilus) is a small, charismatic saltwater fish found in the rocky and coral reef environments along the Pacific coast of Mexico, including the Gulf of California. They often inhabit empty barnacle shells or crevices in rocks, where they can poke their heads out to observe their surroundings. Feeds primarily on zooplankton (small drifting animals). Also takes mobile benthic crustaceans such as small shrimps and crabs, and will eat pelagic fish eggs and small benthic worms when available. It is endemic to the Tropical Eastern Pacific, restricted to the Mexican mainland coast and nearby islands:

Northern limit: Mazatlán area in the southeastern Gulf of California (Sea of Cortez), including the Tres Marías Islands.
Southern limit: The Gulf of Tehuantepec on the Pacific coast of Oaxaca, Mexico.
It is an inshore, reef-associated species found on rocky reefs, living in empty barnacles and worm/mollusk tubes at 1–15 m.

So its range is a relatively narrow band along the west coast of Mexico, from southern Gulf of California south through the mainland Pacific coast to the Gulf of Tehuantepec.

Diet

Small carnivorous/planktivorous fish that feeds primarily on zooplankton.
It also takes small benthic crustaceans, worms, and pelagic fish eggs from the surrounding water.

Range

Endemic to the tropical eastern Pacific, ranging from southern Baja California and the southern and central Gulf of California south along the Mexican Pacific coast to Guerrero.
It occurs in the Zihuatanejo area, with records from Ixtapa-Zihuatanejo and nearby Guerrero waters.

Habitat

Inhabits shallow rocky reefs, usually from about 1–15 metres.
It occupies empty barnacle shells and abandoned worm or mollusc tubes, using these small cavities as permanent shelters.
It is generally associated with the reef bottom rather than swimming freely in the water column.

Description

Small, elongated tube blenny reaching about 6 cm in total length.
Head is relatively long and blunt, with short pointed spines arranged in a diamond-shaped patch behind and between the eyes.
Head is greyish-brown and densely covered with pale blue spots; the iris is reddish above and black below with a thin cream-coloured inner ring.
Body is brown to tan, with a row of large dark brown spots or blotches along the side and dark saddle-like markings along the base of the dorsal fin.
The front of the dorsal fin is red and normally has a rounded black spot covering the bases of the first two spines.
The lower jaw has a distinctive red central area, while the front portion is creamy white.