Identification: Arapaima, also known as Pirarucu, are large Neotropical fish with robust cylindrical bodies that become laterally compressed towards their posterior end (tail). Their heads are heavily sculptured with bony plates, and taper to a prominent lower jaw that protrudes upward. The mouth contains a bony structure that is covered in small griping teeth, which distinguishes the family, giving them the name bony tongue fishes (Ferraris 2003; Queiroz 2000). In the wild, juvenile Arapaima have a dark brown coloration, which beings to lighten as they age. Darker patches may be present on their dorsal surface, and red markings begin to appear on their posterior end becoming more prominent as they reach maturity (Queiroz 2000). Arapaima have large, heavily mineralized cycloid scales that form an armor-like exterior that protects them from predators such as Piranhas (Ferraris 2003; Queiroz 2000; Yang et al. 2014).
Until the work of Stewart (2013a), the genus Arapaima was thought to be monotypic, with Arapaima gigas considered as the only valid species (Castello and Stewart 2010; Hill and Lawson 2015). His reclassification of A. agassizii (Stewart 2013a), and description of new species (Stewart 2013b) uncovered hidden diversity within the genus, identifying a total of 5 distinct species. These species include A. gigas, A. mapae, A. arapaima, A. agassizii, and A. leptosome. Stewart (2013a) and (2013b) present a detailed diagnosis of major morphological features that distinguish these 5 distinct Arapaima species.
References: (click for full references)
Arantes, C. C., L. Castello, D. J. Stewart, M. Certa, and H. L. Quieroz. 2010. Population density, growth and reproduction of Arapaima in an Amazonian river-floodplain. Ecology of Freshwater Fish 19:455–465.
Castello, L. 2008. Lateral migration of Arapaima gigas in floodplains of the Amazon. Ecology of Freshwater Fish 17(1):38-46.
Castello, L., and D.J. Stewart. 2010. Assessing CITES non-detriment findings procedures for Arapaima in Brazil. Journal of Applied Ichthyology 26(1):49-56.
Fadjar, M., R.A. Islamy, and E.Y. Herawati. 2019. First record of Arapaima gigas (Schinz, 1822) (Teleostei: Osteoglossomorpha), in the Brantas River, Sidoarjo, East Java, Indonesia. Biodiversitas Journal of Biological Diversity, 20(12).
Ferraris, C. J., Jr. 2003. Family Arapaimatidae (Bonytongues), p. 31. In: Check List of the Freshwater Fishes of South and Central America. R. E. Reis, S. O. Kullander, and C. J. Ferraris, Jr. (eds.). EDIPUCRS, Porto Alegre, Brazil.
Hrbek, T., I.P. Farias, M. Crossa, I. Sampaio, J.I. Porto, and A. Meyer. 2005. Population genetic analysis of Arapaima gigas, one of the largest freshwater fishes of the Amazon basin: implications for its conservation. Animal Conservation 8(3):297-308.
Hill, J.E., and K.M. Lawson. 2015. Risk screening of Arapaima, a new species proposed for aquaculture in Florida. North American Journal of Fisheries Management 35:885-894.
Miranda-Chumacero, G., R. Wallace, H. Calderón, G. Calderón, P. Willink, M. Guerrero, T.M. Siles, K. Lara, and D. Chuqui. 2012. Distribution of arapaima (Arapaima gigas) (Pisces: Arapaimatidae) in Bolivia: implications in the control and management of a non-native population. BioInvasions Record, 1(2).
Queiroz, H.L. 2000. Natural history and conservation of pirarucu, Arapaima gigas, at the Amazonian Várzea: red giants in muddy waters. Ph.D. Thesis. St. Andrews (UK): University of St. Andrews, 226 pp.
Stewart, D.J. 2013a. Re-description of the Arapaima agassizii (Valenciennes), a rare fish from Brazil (Osteoglossomorpha: Osteoglossidae). Copeia 1:38-51.
Stewart, D.J. 2013b. A new species of Arapaima (Osteoglossomorpha: Osteoglossidae) from the Solimões River, Amazonas State, Brazil. Copeia 3:470-476.
Yang, W., V. Sherman, B. Gludovatz, M. Mackey, E.A. Zimmermann, E.H. Chang, E. Schaible, Z. Qin, M.J. Buehler, R.O. Ritchie, and M.A. Meyers. 2014. Protective role of Arapaima gigas fish scales: structure and mechanical behavior. Acta biomaterialia 10(8):3599-3614.
This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.