The

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...

fish Fish are Aquatic animal, aquatic, craniate, gill-bearing animals that lack Limb (anatomy), limbs with Digit (anatomy), digits. Included in this definition are the living hagfish, lampreys, and Chondrichthyes, cartilaginous and bony fish as we ...

of tropical South and Central America represent one of the most diverse and extreme aquatic

ecosystem An ecosystem (or ecological system) consists of all the organisms and the physical environment with which they interact. These biotic and abiotic components are linked together through nutrient cycles and energy flows. Energy enters the syst ...

s on Earth, with more than 5,600

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriat ...

, representing about 10% all living

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...

species. The exceptional diversity of species, adaptations, and life histories observed in the

Neotropic The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In ...

al ichthyofauna has been the focus of numerous books and scientific papers, especially the wonderfully complex aquatic ecosystems of the

Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Boli ...

and adjacent river basins (e.g., Goulding and Smith, 1996; Araujo-Lima and Goulding, 1997; Barthem and Goulding, 1997; Barthem, 2003; Goulding et al., 2003). Many of the advances in Neotropical

ichthyology Ichthyology is the branch of zoology devoted to the study of fish, including bony fish ( Osteichthyes), cartilaginous fish ( Chondrichthyes), and jawless fish ( Agnatha). According to FishBase, 33,400 species of fish had been described as of Oct ...

have been summarized in three edited volumes: Malabarba et al. (1998); Reis et al. (2003); Albert and Reis (2011). The Neotropical ichthyofauna extends throughout the continental waters of Central and South America, from south of the Mesa Central in southern Mexico (~ 16° N) to the La Plata estuary in northern Argentina (~ 34° S). The fishes of this region are largely restricted to the humid tropical portions of the Neotropical realm as circumscribed by Sclater (1858) and Wallace (1876), being excluded from the arid Pacific slopes of Peru and northern Chile, and the boreal regions of the Southern Cone in Chile and Argentina (Arratia, 1997; Dyer, 2000). The vast Neotropical ichthyofaunal region extends over more than 17 million square km of moist tropical lowland forests, seasonally flooded wetlands and savannahs, and also several arid peripheral regions (e.g., Northwest Venezuela; Northeast Brazil; Chaco of Paraguay, Argentina and Bolivia). At the core of this system lies Amazonia, the greatest interconnected freshwater fluvial system on the planet. This system includes the drainages of the Amazon Basin itself, and of two large adjacent regions, the Orinoco Basin and the Guiana Shield. The

Amazon river The Amazon River (, ; es, Río Amazonas, pt, Rio Amazonas) in South America is the largest river by discharge volume of water in the world, and the disputed longest river system in the world in comparison to the Nile. The headwaters of t ...

is by any measure the largest in the world, discharging about 16% of the world's flowing freshwater into the Atlantic (Goulding et al., 2003b).

Notes and references

{{Reflist Fish by habitat Aquatic ecology Ichthyology