Mexican nightsergeant – Abudefduf declivifrons

The Mexican Nightsergeant (Abudefduf declivifrons) is a species of marine fish belonging to the damselfish family, Pomacentridae. This colorful fish is recognized for its striking appearance and its adaptation to a specific range of marine habitats.

Description & Characteristics

The Mexican Nightsergeant (Abudefduf declivifrons) can reach a maximum size of 18.0 cm. Its body is generally oval-shaped with a slightly compressed profile. The fish boasts a vibrant coloration, characterized by a black body with a white band running horizontally along its upper side. This band is typically broader and more prominent near the head, extending towards the tail. The fins are typically dark gray to black, contrasting with the white band.

Habitat and Occurrence

The Mexican Nightsergeant (Abudefduf declivifrons) displays a preference for shallow, coastal waters, typically inhabiting the Intertidal (Eulittoral) zone, which is the intertidal zone between the high and low tide lines characterized by the alternation of low and high tides. This adaptation allows the species to thrive in areas exposed to fluctuations in water levels and temperature. They are commonly found in rocky reefs, coral reefs, and seagrass beds, seeking shelter among the crevices and vegetation. They can be observed at depths ranging from 1.0 to 5.0 meters.

Taxonomy

The Mexican Nightsergeant (Abudefduf declivifrons) is classified within the Class: Teleostei, Order: Ovalentaria incertae sedis, and Family: Pomacentridae. This classification places it among the ray-finned fishes, a diverse group characterized by their bony skeletons and fins supported by rays.

Feeding

The Mexican Nightsergeant (Abudefduf declivifrons) is a predatory fish with a varied diet. Their opportunistic feeding habits encompass a range of prey items including: amphipods, carrion, copepods, Daphnia salina, detritus, small fishes, fish eggs, fish larvae, invertebrates, krill, living food, mysis, shrimps, and worms. They also consume zooplankton, contributing to the balance of the marine ecosystem.