''Mylossoma duriventre'', the silver mylossoma, is a species of freshwater

serrasalmid The Serrasalmidae (serrasalmids) are a family of characiform fishes, recently elevated to family status. It includes more than 90 species. The name means "serrated salmon family", which refers to the serrated keel running along the belly of these ...

fish

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 ...

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

and

subtropical The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Geographical z ...

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. It grows to a maximum length of about and a weight of . It is the subject of a local

fishery Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life; or more commonly, the site where such enterprise takes place ( a.k.a. fishing ground). Commercial fisheries include wild fisheries and fish farms, both ...

, being known as

pacu Pacu () is a common name used to refer to several species of omnivorous South American freshwater serrasalmid fish that are related to the piranha. Pacu and piranha do not have similar teeth, the main difference being jaw alignment; piranha hav ...

in Brazil and

palometa Palometa is a name used for several species of fish: ;Freshwater *''Catoprion mento'', the wimple piranha from several South American river basins *''Metynnis'', a genus of serrasalmid from several South American river basins *''Myloplus rubripinn ...

in Venezuela (names it shares with several relatives).

Distribution and habitat

As traditionally defined, ''Mylossoma duriventre'' 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 technology c ...

Orinoco The Orinoco () is one of the longest rivers in South America at . Its drainage basin, sometimes known as the Orinoquia, covers , with 76.3 percent of it in Venezuela and the remainder in Colombia. It is the fourth largest river in the wor ...

and

Río de la Plata The Río de la Plata (, "river of silver"), also called the River Plate or La Plata River in English, is the estuary formed by the confluence of the Uruguay River and the Paraná River at Punta Gorda. It empties into the Atlantic Ocean and fo ...

basins, and to the

Tocantins River The Tocantins River ( pt, Rio Tocantins, link=no , , Parkatêjê dialect, Parkatêjê: ''Pyti'' ɨˈti is a river in Brazil, the central fluvial artery of the country. In the Tupi language, its name means "toucan's beak" (''Tukã'' for "toucan ...

and its western tributary, the

Araguaia River The Araguaia River ( pt, Rio Araguaia , Karajá: ♂ ''Berohokỹ'' eɾohoˈkə̃ ♀ ''Bèrakuhukỹ'' ɛɾakuhuˈkə̃ is one of the major rivers of Brazil though it is almost equal in volume at its confluence with the Tocantins. It has a total ...

. It prefers nutrient-rich waters but also occurs in the lower stretches of nutrient-poor rivers. In 2018, a review based on DNA and

morphometrics Morphometrics (from Greek μορϕή ''morphe'', "shape, form", and -μετρία ''metria'', "measurement") or morphometry refers to the quantitative analysis of ''form'', a concept that encompasses size and shape. Morphometric analyses are co ...

restricted its range to the Río de la Plata Basin (

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

, lower Paraná and

Uruguay Uruguay (; ), officially the Oriental Republic of Uruguay ( es, República Oriental del Uruguay), is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast; while bordering ...

rivers). Two species formerly considered

synonyms A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...

of ''M. duriventre'' have been revalidated: '' M. albiscopum'' of the Amazon and Orinoco basins, and '' M. unimaculatum'' of the Tocantins–Araguaia basin.

Ecology

This species is

potamodromous Fish migration is animal migration, mass relocation by fish from one area or body of water to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few ...

, migrating entirely within freshwater habitats. The migration pattern is not fully understood, but in the flood season in the Amazon, between December and March, the fish migrate from the lakes and pools on the

floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river which stretches from the banks of its channel to the base of the enclosing valley walls, and which experiences flooding during periods of high discharge.Goudi ...

to the larger rivers. Here they move upstream in large numbers to the

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...

areas, although precisely where the fish spawn is unclear. The adults then move out of the rivers and onto the floor of the forest when this floods. The larvae meanwhile are swept downstream, and when the forest floods, spread out into nursery areas on the floodplain where their

plankton Plankton are the diverse collection of organisms found in Hydrosphere, water (or atmosphere, air) that are unable to propel themselves against a Ocean current, current (or wind). The individual organisms constituting plankton are called plankt ...

ic food is more readily available. When the waters recede, both adults and juvenile fish move back into the rivers and move upstream to the floodplain lakes. In the seasonally-flooded

várzea forest A várzea forest is a seasonal floodplain forest inundated by whitewater rivers that occurs in the Amazon biome. Until the late 1970s, the definition was less clear and várzea was often used for all periodically flooded Amazonian forests. Althoug ...

, this fish is often found living in close association with ''

Potamorhina ''Potamorhina'' is a genus of toothless characin from South America, with these currently described species: * '' Potamorhina altamazonica'' (Cope, 1878) * '' Potamorhina laticeps'' (Valenciennes, 1850) * '' Potamorhina latior'' (Spix & Agassiz ...

altamazonica''. Juvenile ''M. duriventre'' feed on insects and adults feed on fruits and seeds.

Threats

In parts of its range, ''M. duriventre'' is considered to be a vulnerable species. The threats it faces include the encroachment of agriculture on the forest habitat, mining,

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

schemes, overfishing, tourism and recreational activities. The seasonal flooding of the forest is important for the survival of the larvae of this fish.

References

{{Taxonbar, from=Q6417131 Serrasalmidae Fish of South America Fish described in 1818 Taxa named by Georges Cuvier