The silver arowana (''Osteoglossum bicirrhosum'') is a South American freshwater bony fish of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Osteoglossidae Osteoglossidae is a family of large freshwater fish, which includes the arowanas and arapaima. The family contains two subfamilies Arapaiminae and Osteoglossinae, with a total of five living genera. Osteoglossids are basal teleosts that origin ...

. Silver arowanas are sometimes kept in aquariums, but they are predatory and require a very large tank. The generic name ''Osteoglossum'' means "bone-tongued" and the specific name ''bicirrhosum'' means "two barbels" (from the

Greek language Greek ( el, label= Modern Greek, Ελληνικά, Elliniká, ; grc, Ἑλληνική, Hellēnikḗ) is an independent branch of the Indo-European family of languages, native to Greece, Cyprus, southern Italy ( Calabria and Salento), southe ...

Range and habitat

This South American species is native to the

Amazon Amazon most often refers to: * Amazons, a tribe of female warriors in Greek mythology * Amazon rainforest, a rainforest covering most of the Amazon basin * Amazon River, in South America * Amazon (company), an American multinational technolog ...

, Essequibo and

Oyapock The Oyapock or Oiapoque (; ; ) is a long river in South America that forms most of the border between the French overseas department of French Guiana and the Brazilian state of Amapá. Course The Oyapock runs through the Guianan moist fores ...

basins. It is absent from the Rio Negro basin, except the Branco River, which is inhabited by both silver and

black arowana The black arowana (''Osteoglossum ferreirai'') is a South American freshwater bony fish of the family Osteoglossidae. Black arowanas are sometimes kept in aquariums, but they are predatory and require a very large tank. It is generally common, b ...

s. The silver arowana occurs in both black- and

whitewater Whitewater forms in a rapid context, in particular, when a river's gradient changes enough to generate so much turbulence that air is trapped within the water. This forms an unstable current that froths, making the water appear opaque and ...

habitats, including flooded forests.

Description

This fish has relatively large scales, a long body, and a tapered tail, with the dorsal and anal fins extending all the way to the small caudal fin, with which they are nearly fused. Its maximum total length is typically considered to be , but there are reports of individuals up to . Unlike the

, the silver arowana has the same coloring throughout its lifespan. Adults of the two species are very similar, but can be separated by

meristics Meristics is an area of ichthyology and herpetology which relates to counting quantitative features of fish and reptiles, such as the number of fins or scales. A meristic (countable trait) can be used to describe a particular species of fish, or us ...

Arowana Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). In this family of fish, the head is bony and the elongated body is covered by large, heavy sc ...

s are sometimes called 'dragon fish' by aquarists because their shiny, armor-like scales and double barbels are reminiscent of descriptions of dragons in East Asian folklore.

Behavior

The species is also called 'water monkey' because of its ability to jump out of the water and capture its

prey Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

. It usually swims near the water surface waiting for potential prey. Although specimens have been found with the remains of birds,

bat Bats are mammals of the order Chiroptera.''cheir'', "hand" and πτερόν''pteron'', "wing". With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most ...

s, mice, and snakes in their stomachs, its main diet consists of snails, crustaceans (such as crabs), insects (such as beetles), spiders, smaller fish, and other animals that float on the water surface, which its drawbridge-like mouth is exclusively adapted for feeding on.

Conservation status

The silver arowana is currently not listed on any

CITES CITES (shorter name for the Convention on International Trade in Endangered Species of Wild Fauna and Flora, also known as the Washington Convention) is a multilateral treaty to protect endangered plants and animals from the threats of interna ...

appendix nor on the 2004

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

. It is one of the most popular ornamental fish from South America, however, and therefore its

conservation status The conservation status of a group of organisms (for instance, a species) indicates whether the group still exists and how likely the group is to become extinct in the near future. Many factors are taken into account when assessing conservatio ...

merits attention. As reported by '' Environment News Service'' in August 2005, shared use of the silver arowana population was a cause for a dispute between

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 ...

ian and Colombian authorities. Juvenile silver arowanas are caught in Colombia for sale as aquarium fish, while the people of

ian Amazonia catch adult fish for food. A sharp drop in the number of arowanas had caused Brazilian authorities to prohibit fishing of them between September 1 and November 15; the Colombians would prohibit capturing them between November 1 and March 15.Brazil, Colombia at Odds Over Silver Amazon Fish
A meeting between the representatives of the Amazon Basin countries in August 2005 was meant to discuss the dispute. The silver arowana is often kept as a pet by experienced aquarists, being considered an accessible substitute for the

Asian arowana The Asian arowana (''Scleropages formosus'') comprises several phenotypic varieties of freshwater fish distributed geographically across Southeast Asia. While most consider the different varieties to belong to a single species, work by Pouyaud ...

, which is listed on CITES Appendix I and is therefore difficult and expensive to obtain legally.

References