''Melanorivulus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

of South American

freshwater fish Freshwater fish are those that spend some or all of their lives in fresh water, such as rivers and lakes, with a salinity of less than 1.05%. These environments differ from marine conditions in many ways, especially the difference in levels of s ...

in 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 ...

Rivulidae The Rivulidae are a family of killifishes in the order Cyprinodontiformes. They are commonly known as rivulids, South American killifish or New World killifish. The latter names are slightly misleading, however, as they are neither restricted to ...

. Most species are

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 els ...

to the

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 f ...

, eastern

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 ...

(west to

Tapajós The Tapajós ( pt, Rio Tapajós ) is a river in Brazil. It runs through the Amazon Rainforest and is a major tributary of the Amazon River. When combined with the Juruena River, the Tapajós is approximately long. It is one of the largest cle ...

basin),

Tocantins Tocantins () is one of the 26 states of Brazil. It is the newest state, formed in 1988 and encompassing what had formerly been the northern two-fifths of the state of Goiás. Tocantins covers and had an estimated population of 1,496,880 in 2 ...

– Araguaia and São Francisco basins in Brazil, but a few members of this genus range west into Bolivia, south into Paraguay and Argentina, and east to

Parnaíba Parnaíba () is a city in the Brazilian state of Piauí. Having a population of over 150,000 inhabitants according to IBGE's 2020 report, it is the second most populous city in the state, after the capital Teresina. It is one of the four coast ...

and

Sergipe Sergipe (), officially State of Sergipe, is a state of Brazil. Located in the Northeast Region along the Atlantic coast of the country, Sergipe is the smallest state in Brazil by geographical area at , larger only than the Federal District. S ...

in northeastern Brazil. Only ''M. schuncki'' occurs north of the Amazon River.Costa, W.J.E.M., Bragança, P.H.N. & Ottoni, F.P. (2015)
A new miniature killifish of the genus ''Melanorivulus'' (Cyprinodontiformes: Rivulidae) from the coastal plains of north-eastern Brazil.
''Vertebrate Zoology, 65 (1): 31–35.'' They inhabit shallow waters, generally deep, at the margins of streams in open or fairly open habitats like the

Cerrado The ''Cerrado'' (, ) is a vast ecoregion of tropical savanna in eastern Brazil, particularly in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Minas Gerais, and the Federal District. The core areas of the Cerrado biome are ...

or Cerrado–Amazon transition. Many have tiny ranges and are seriously

threatened Threatened species are any species (including animals, plants and fungi) which are vulnerable to endangerment in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensa ...

.Costa, W.J.E.M. (2012)
Two new species of ''Melanorivulus'' from the Caiapós hill, upper Araguaia river basin, Brazil (Cyprinodontiformes: Rivulidae).
''Ichthyological Exploration of Freshwaters, 23 (3): 211-218.'' Similar to closely related genera such as ''

Anablepsoides ''Anablepsoides'' is a genus of killifish in the family Rivulidae native to tropical South America and the Lesser Antilles. The majority are from the Amazon and Orinoco basins, as well as freshwater systems in the Guiana Shield, but a few spe ...

'', ''

Atlantirivulus ''Atlantirivulus'' is a genus of fishes in the family Rivulidae. They are endemic to shallow swamps, creeks, streams and pools in the Atlantic Forest in southeastern Brazil, ranging from Rio de Janeiro to Santa Catarina.Costa, W.J.E.M. (2014)F ...

'', ''

Cynodonichthys ''Cynodonichthys'' is a genus of freshwater killifish in the family Rivulidae. They are found in Middle America, ranging from southern Mexico (north to Oaxaca and the Yucatán Peninsula), through Central America (where most species live), to ...

'' and ''

Laimosemion ''Laimosemion'' is a genus of fish in the family Rivulidae from the Amazon basin and basins in the Guiana Shield in tropical South America. They mostly inhabit small streams, creeks, swamps and pools in lowlands, but locally occur to an altitud ...

'', ''Melanorivulus'' are jumpers and non-annual

killifish A killifish is any of various oviparous (egg-laying) cyprinodontiform fish (including families Aplocheilidae, Cyprinodontidae, Fundulidae, Profundulidae and Valenciidae). All together, there are 1,270 species of killifish, the biggest famil ...

. ''Melanorivulus'' are small fish, with the largest species up in

total length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish ...

and the smallest less than . They are often quite colorful and some are kept in aquariums.

Species

Until 2011, ''Melanorivulus'' were included in ''

Rivulus ''Rivulus'' is a genus of small freshwater fish in the Cyprinodontiformes family Rivulidae. It was traditionally considered to be the largest genus in its family; however, the genus's size is currently in dispute. Wilson J. E. Costa split this ge ...

'', and some prefer to maintain them in that genus. If recognized as a valid genus, there are currently 60 species in ''Melanorivulus'': * ''

Melanorivulus amambaiensis ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, ...

'' Volcan, Severo-Neto & Lanés, 2018 * ''

Melanorivulus apiamici ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, ...

'' ( W. J. E. M. Costa, 1989) * ''

Melanorivulus atlanticus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, ...

'' W. J. E. M. Costa, Bragança & Ottoni, 2015 * ''

Melanorivulus bororo ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, ...

'' ( W. J. E. M. Costa, 2008) * ''

Melanorivulus britzkei ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, ...

'' Nielsen, 2017 * ''

Melanorivulus canesi ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, ...

'' Nielsen, 2017 * '' Melanorivulus crixas'' ( W. J. E. M. Costa, 2007) * ''

Melanorivulus cyanopterus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2005) * '' Melanorivulus dapazi'' ( W. J. E. M. Costa, 2005) * '' Melanorivulus decoratus'' ( W. J. E. M. Costa, 1989) * ''

Melanorivulus egens ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2005) * ''

Melanorivulus faucireticulatus ''Melanorivulus'' is a genus of South American freshwater fish in the family (biology), family Rivulidae. Most species are Endemism, endemic to the Río de la Plata Basin, Río de la Plata, eastern Amazon basin, Amazon (west to Tapajós River, Ta ...

'' ( W. J. E. M. Costa, 2008) * '' Melanorivulus flavipinnis'' W. J. E. M. Costa, 2017Costa, W.J.E.M. (2017)
Three new species of the killifish genus ''Melanorivulus'' from the central Brazilian Cerrado savanna (Cyprinodontiformes, Aplocheilidae).
''ZooKeys, 645: 51–70.'' * '' Melanorivulus formosensis'' ( W. J. E. M. Costa, 2008) * '' Melanorivulus giarettai'' ( W. J. E. M. Costa, 2008) * ''

Melanorivulus ignescens ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' W. J. E. M. Costa, 2017 * ''

Melanorivulus illuminatus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2007) * '' Melanorivulus imperatrizensis'' D. T. B. Nielsen & C. S. Pinto, 2015Nielsen, D.T.B. & Pinto, C.S. (2015)
''Melanorivulus imperatrizensis'', a new species of killifish (Cyprinodontiformes: Rivulidae) from the rio Tocantins basin, Brazil.
''aqua, International Journal of Ichthyology, 21 (3): 136-143.'' * '' Melanorivulus interruptus'' Volcan, Severo-Neto & Lanés, 2018 * '' Melanorivulus ivinhemensis'' Volcan, Severo-Neto & Lanés, 2018 * '' Melanorivulus jalapensis'' ( W. J. E. M. Costa, 2010)Costa, W.J.E.M. (2010)
''Rivulus jalapensis'', a new killifish from the Tocantins River basin, central Brazil (Cyprinodontiformes: Rivulidae).
''Ichthyological Exploration of Freshwaters, 21 (3): 193-198.'' * '' Melanorivulus javahe'' ( W. J. E. M. Costa, 2007) * '' Melanorivulus karaja'' ( W. J. E. M. Costa, 2007) * '' Melanorivulus kayabi'' ( W. J. E. M. Costa, 2008) * ''

Melanorivulus kayapo ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2006) * ''

Melanorivulus kunzei ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' W. J. E. M. Costa, 2012 * ''

Melanorivulus leali ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' W. J. E. M. Costa, 2013Costa, W.J.E.M. (2013)
A new killifish of the genus ''Melanorivulus'' from the upper Paraná river basin, Brazil (Cyprinodontiformes: Rivulidae).
''Vertebrate Zoology, 63 (3): 277-281.'' * ''

Melanorivulus linearis ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' W. J. E. M. Costa, 2018 * ''

Melanorivulus litteratus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2005) * '' Melanorivulus megaroni'' ( W. J. E. M. Costa, 2010)Costa, W.J.E.M. (2010)
''Rivulus megaroni'', a new killifish from the Xingu River drainage, southern Brazilian Amazon (Cyprinodontiformes: Rivulidae).
''Ichthyological Exploration of Freshwaters, 20 (4): 365-370.'' * '' Melanorivulus modestus'' ( W. J. E. M. Costa, 1991) * '' Melanorivulus nelsoni'' Volcan, Severo-Neto & Lanés, 2017 * '' Melanorivulus nigromarginatus'' W. J. E. M. Costa, 2018 * ''

Melanorivulus nigropunctatus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' Volcan, Klotzel & Lanés, 2017Volcan, M.V., Klotzel, B. & Lanés, L.E.K. (2017): Two new species of ''Melanorivulus'' (Cyprinodontiformes: Cynolebiidae) from Rio Verde drainage, Upper Rio Paraná basin, Brazil. ''Zootaxa, 4236 (1): 82-94.'' * '' Melanorivulus ofaie'' Volcan, Klotzel & Lanés, 2017 * '' Melanorivulus paracatuensis'' ( W. J. E. M. Costa, 2003) * ''

Melanorivulus paresi ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2008) * '' Melanorivulus parnaibensis'' ( W. J. E. M. Costa, 2003) * '' Melanorivulus petrisecundi'' W. J. E. M. Costa, 2016Costa, W.J.E.M. (2016)
Comparative morphology, phylogenetic relationships, and taxonomic revision of South American killifishes of the ''Melanorivulus zygonectes'' species group (Cyprinodontiformes: Rivulidae).
''Ichthyological Exploration of Freshwaters, 27 (2): 107-152.'' * '' Melanorivulus pictus'' ( W. J. E. M. Costa, 1989) * '' Melanorivulus pindorama'' W. J. E. M. Costa, 2012Costa, W.J.E.M. (2012)
''Melanorivulus pindorama'', a new killifish from the Tocantins River drainage, central Brazilian Cerrado (Cyprinodontiformes: Rivulidae).
''Ichthyological Exploration of Freshwaters, 23 (1): 57-61.'' * '' Melanorivulus pinima'' ( W. J. E. M. Costa, 1989) * '' Melanorivulus planaltinus'' ( W. J. E. M. Costa &

Brasil 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 an ...

, 2008) * '' Melanorivulus polychromus'' D. T. B. Nielsen, P. A. B. A. Neves, Ywamoto & Passos, 2016Nielsen, D.T.B., Neves, P.A.B.A., Ywamoto, E.V. & Passos, M.d.A. (2016)
''Melanorivulus polychromus'', a new species of killifish from the rio São José dos Dourados drainage, middle rio Paraná basin, southwestern Brazil, with a redescription of ''Melanorivulus apiamici'' (Cyprinodontiformes: Rivulidae).
''aqua, International Journal of Ichthyology, 22 (2): 79-88.'' * '' Melanorivulus proximus'' W. J. E. M. Costa, 2018 * '' Melanorivulus punctatus'' ( Boulenger, 1895) * '' Melanorivulus regularis'' W. J. E. M. Costa, 2017 * '' Melanorivulus rossoi'' ( W. J. E. M. Costa, 2005) * '' Melanorivulus rubromarginatus'' ( W. J. E. M. Costa, 2007) * '' Melanorivulus rubroreticulatus'' W. J. E. M. Costa, Amorim & Bragança, 2014Costa, W.J.E.M., Amorim, P.F. & Bragança, P.H.N. (2014)
A new miniature killifish of the genus ''Melanorivulus'' (Cyprinodontiformes: Rivulidae) from the Xingu river drainage, Brazilian Amazon.
''Vertebrate Zoology, 64 (2): 193-197.'' * '' Melanorivulus rutilicaudus'' ( W. J. E. M. Costa, 2005) * ''

Melanorivulus salmonicaudus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 2007) * '' Melanorivulus scalaris'' ( W. J. E. M. Costa, 2005) * '' Melanorivulus schuncki'' ( W. J. E. M. Costa &

de Luca DeLuca, also spelled Deluca or De Luca, is an Italian-language surname. People with the surname include: People * Adrian Deluca (born 1982), former Australian rules footballer * Alby De Luca (1908–1978), Australian rules footballer * Anthony ...

, 2011)Costa, W.J.E.M. & De Luca, A.C. (2011)
''Rivulus schuncki'', a new species of the killifish subgenus ''Melanorivulus'', from eastern Brazilian Amazon (Cyprinodontiformes: Rivulidae).
''Ichthyological Exploration of Freshwaters, 21 (4): 289-293.'' * ''

Melanorivulus spixi ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' W. J. E. M. Costa, 2016 * '' Melanorivulus ubirajarai'' W. J. E. M. Costa, 2012 * ''

Melanorivulus violaceus ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( W. J. E. M. Costa, 1991) * '' Melanorivulus vittatus'' ( W. J. E. M. Costa, 1989) * '' Melanorivulus wallacei'' W. J. E. M. Costa, 2016 * ''

Melanorivulus zygonectes ''Melanorivulus'' is a genus of South American freshwater fish in the family Rivulidae. Most species are endemic to the Río de la Plata, eastern Amazon (west to Tapajós basin), Tocantins– Araguaia and São Francisco basins in Brazil, but a f ...

'' ( G. S. Myers, 1927)

References

{{Taxonbar, from=Q6811535 Rivulidae Fish of South America Freshwater fish genera