The royal tetra (Inpaichthys kerri) is a species of characin endemic to Brazil, where it is found in tributaries of the Aripuanã River.

[2] 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 specimen was discovered.

In its natural habitat it lives in very soft and slightly acidic waters with a pH between 6.0 and 6.8.

[2] I. kerri is a very active and bold species and has been found schooling with another undescribed species (similar to Hyphessobrycon cachimbensis).It is generally less abundant than the latter, in the ratio 1/200 or less, although it can be quite abundant in some spots.

I. kerri requires similar-sized schooling fish that are not overly aggressive, as this species is prone to diseases when stressed in captivity.