The green terror (''Andinoacara rivulatus'', syn. ''Aequidens rivulatus'') is a colorful

freshwater fish Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes, ponds and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many wa ...

in the

cichlid Cichlids () are a large, diverse, and widespread family of percomorph fish in the family Cichlidae, order Cichliformes. At least 1,760 species have been scientifically described, making it one of the largest vertebrate families, with on ...

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

. The fish originates from the Pacific side of

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

from the

Tumbes River The Tumbes River ( or Río Túmbez in Peru; Río Puyango in Ecuador), is a river in South America. The river's sources are located between Ecuadorian El Oro and Loja provinces. It is the border between El Oro and Loja, and afterwards the border ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

to the

Esmeraldas River The Esmeraldas River is a river in northwestern Ecuador that flows into the Pacific Ocean at the city of Esmeraldas. Among its tributaries is the Guayllabamba River which drains Quito. Charles Marie de la Condamine sailed up it and then climb ...

Ecuador Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...

. It is polymorphic and can have white or gold-orange edging to the tail and

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

s. It has historically been confused with two other species that always have narrow, clearly defined white edging, the more southerly distributed '' A. stalsbergi'' (often considered the "true" green terror) and the more northerly '' A. blombergi''.Musilova, Rican, and Novak (2009). Phylogeny of the Neotropical cichlid fish tribe Cichlasomatini (Teleostei: Cichlidae) based on morphological and molecular data, with the description of a new genus. Journal of Zoological Systematics and Evolutionary Research 47(3): 209—304.Wijkmark, Kullander, and Barriga (2012). Andinoacara blombergi, a new species from the río Esmeraldas basin in Ecuador and a review of A. rivulatus (Teleostei: Cichlidae). Ichthyological Exploration of Freshwaters 23(2): 117—137.

Species

Males of ''A. rivulatus'' grow larger than females and may reach lengths of up to .SeriouslyFish
Andinoacara rivulatus.
Retrieved 7 May 2017. Females are

sexually mature Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized as ...

at around . As the name implies, late juvenile-phase and adult-phase specimens can be very aggressive. This is not guaranteed, however, and peaceful individuals can be observed. Juveniles of ''A. rivulatus'' are often sold in

aquarium An aquarium (: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. fishkeeping, Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquati ...

stores. This species is not to be confused with the blue acara (''A. pulcher'') which is similar in appearance; the blue acara is not as aggressive and does not grow as large as the gold saum. The fish is somewhat deep-bodied, possessing a prominent forehead. Adult males develop a pronounced forehead hump, composed of fatty tissue. Juveniles are tan colored with silver-blue flecks and lack the bright

iridescent Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear gradually to change colour as the angle of view or the angle of illumination changes. Iridescence is caused by wave interference of light in microstruc ...

blue, green, and orange coloration and long, flowing fins of adult specimens. In nature, ''A. rivulatus'' lives in a

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

climate and prefers water with a 6.5–8.0 pH, a water hardness of 25.0 dGH, and a temperature range of .

In the aquarium

''A. rivulatus'' is a popular fish in the aquarium trade and is noted for its hardiness, as well as its aesthetic appeal. The fish may grow up to in length, though lengths are more typical, fish do not grow based on the size of their

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

. ''A. rivulatus'' is an inherently aggressive fish. With the exception of fully mature ''P. dovii'' (wolf cichlid) and ''P. managuense'' (jaguar cichlid), which rarely cohabit peacefully, ''A. rivulatus'' is cunning enough to survive—and even thrive—with larger cichlids. However, as a rule, a preying cichlid is capable of consuming any animal whose dimensions are inferior to that of the cichlid's fully expanded jaw. ''A. rivulatus'' of an appropriate size can often be assimilated with ''R. octofasciata'' (Jack Dempsey cichlid), ''A. citrinellus'' (midas cichlid), ''T. meeki'' (firemouth cichlid), flowerhorns (no scientific designation), smaller '' P. managuense (jaquar cichlid)'' and ''P. dovii'' (wolf cichlid), and other similarly aggressive cichlids.

Role in hormone research

''A. rivulatus'' has also been used as a model for the effects of testosterone on

lateralization The lateralization of brain function (or hemispheric dominance/ lateralization) is the tendency for some neural functions or cognitive processes to be specialized to one side of the brain or the other. The median longitudinal fissure separates ...

References

General

* {{Taxonbar, from=Q3681 Green terror Cichlid fish of South America Freshwater fish of Ecuador Freshwater fish of Peru Fish described in 1860 Taxa named by Albert Günther

Species

In the aquarium

Role in hormone research

See also

References

General