The royal tetra (''Inpaichthys kerri'') is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

characin Characiformes is an order of ray-finned fish, comprising the characins and their allies. Grouped in 18 recognized families, more than 2000 different species are described, including the well-known piranha and tetras.; Buckup P.A.: "Relationshi ...

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

, where it is found in tributaries of the

Aripuanã River Aripuanã River ( pt, Rio Aripuanã) is a river in the Mato Grosso and Amazonas states in north-western Brazil. It is a tributary of the Madeira River in the Amazon Basin. The town of Novo Aripuanã is located on its banks where it merges into th ...

. It is the sole member of its genus. The fish was named in honor of Warwick Estevam Kerr (1922-2018), a Brazilian agricultural engineer, geneticist, entomologist, and director of INPA the acronym for Instituto Nacional de Pesquisas da Amazônia, whose field station in Núcleo Aripuanã, Mato Grosso, Brazil, is near the area where the type was found.

Ecology

''Inpaichthys kerri'' was discovered in sunny and moving waters of the forested Queimada river system, a tributary of the Aripuanã River. In its natural habitat it lives in very soft and slightly acidic waters with a pH between 6.0 and 6.8. ''I. kerri'' is a very active and bold species and has been found schooling with another undescribed species (similar to Hyphessobrycon cachimbensis), and is generally less abundant than the latter, in the ratio 1/200 or less, although it can be quite abundant in some spots. It feeds mainly on insects that fell on the water surface.

In captivity

It is kept as an

aquarium An aquarium (plural: ''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. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aq ...

fish where it is sold under the additional common names blue emperor tetra, purple emperor tetra, black emperor tetra, or regal tetra (not to be confused with

Nematobrycon palmeri ''Nematobrycon palmeri'', commonly known as the emperor tetra, is a species of characid fish found in the Atrato and San Juan river basins in western Colombia. It was first imported in the aquarium trade to the United States in 1960 and has s ...

with similar appearance and common names). ''I. kerri'' requires similar-sized schooling fish that are not overly aggressive, as this species is prone to diseases when stressed in captivity.

References

* {{Taxonbar, from=Q1796454 Characidae Monotypic fish genera Fish of South America Fish of Brazil Endemic fauna of Brazil Fish described in 1977 Taxa named by Jacques Géry Taxa named by Wolfgang Johannes Junk