''Abudefduf declivifrons'', commonly known as the Mexican nightsergeant, is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

damselfish Damselfish are those fish within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastinae within the family Pomacentridae. Most species within this group are relatively small, although the four largest speci ...

in the family

Pomacentridae Pomacentridae is a family of ray-finned fish, comprising the damselfishes and clownfishes. This family were formerly placed in the order Perciformes or as indeterminate percomorphs, but are now considered basal blenniiforms. They are primaril ...

native to the eastern Pacific Ocean. It is known only from Mexico, where it ranges from the

Gulf of California The Gulf of California (), also known as the Sea of Cortés (''Mar de Cortés'') or Sea of Cortez, or less commonly as the Vermilion Sea (''Mar Vermejo''), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from ...

Acapulco Acapulco de Juárez (), commonly called Acapulco ( , ; ), is a city and Port of Acapulco, major seaport in the Political divisions of Mexico, state of Guerrero on the Pacific Coast of Mexico, south of Mexico City. Located on a deep, semicirc ...

. It is typically found in surge-exposed rocky

reefs A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic (non-living) processes such as deposition of sand or wave eros ...

at a depth of . It is an

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

species, with individuals forming distinct pairs during breeding and males guarding and aerating eggs. The species reaches in

standard length Fish measurement is the measuring of individual fish and various parts of fish anatomy, their anatomies, for data used in many areas of ichthyology, including Taxonomy (biology), taxonomy and fishery biology. Overall length Standard length (SL) is ...

References

declivifrons Fish of Mexico Fish of the Gulf of California {{Pomacentridae-stub