Arapaima

The arapaima, pirarucu, or paiche are any large species of bonytongue in the genus Arapaima native to the Amazon and Essequibo basins of South America. Genus Arapaima is the type genus of the family Arapaimidae. They are among the world's largest freshwater fish, reaching as much as 3 m (9.8 ft). They are an important food fish. They have declined in the native range due to overfishing and habitat loss. In contrast, arapaima have been introduced to several tropical regions outside the native range (within South America and elsewhere) where they are sometimes considered invasive species. Its Brazilian Portuguese name, pirarucu, derives from the Tupi language words pira and urucum, meaning 'red fish'. Arapaima was traditionally regarded as a monotypic genus, but later several species were distinguished. As a consequence of this taxonomic confusion, most earlier studies were done using the name A. gigas, but this species is only known from old museum specimens and the exact native range is unclear. The regularly seen and studied species is A. arapaima, although a small number of A. leptosoma also have been recorded in the aquarium trade. The remaining species are virtually unknown: A. agassizii from old detailed drawings (the type specimen itself was lost during World War II bombings) and A. mapae from the type specimen. A. arapaima is relatively thickset compared to the remaining species. FishBase recognizes four species in the genus. In addition to these, evidence suggests that a fifth species, A. arapaima, should be recognized (this being the widespread, well-known species, otherwise included in A. gigas). These fish are widely dispersed and do not migrate, which leads scientists to suppose that more species are waiting to be discovered among the depths of the Amazon Basin harbors. Sites such as these offer the likelihood of diversity.