''Melanorivulus'' is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of South American

freshwater fish Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers, lakes, ponds and inland wetlands, where the salinity is less than 1.05%. These environments differ from marine habitats in many wa ...

in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Rivulidae. Most species are

endemic Endemism is the state of a species being found only 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 foun ...

to the

Río de la Plata The Río de la Plata (; ), 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, Colonia, Punta Gorda. It empties into the Atlantic Ocean and ...

, eastern

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

(west to Tapajós 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 2014 ...

– 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 169,000 inhabitants according to IBGE's 2024 estimates, 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 States of Brazil, state of Brazil. Located in the Northeast Region, Brazil, Northeast Region along the Atlantic Ocean, Atlantic coast of the country, Sergipe is the smallest state in Brazil by geogra ...

in northeastern Brazil. Only ''M. schuncki'' occurs north of the Amazon River. 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 Tropics, tropical savanna in central Brazil, being present in the states of Goiás, Mato Grosso do Sul, Mato Grosso, Tocantins, Maranhão, Piauí, Bahia, Minas Gerais, São Paulo (state), São Paulo, Paraná ...

or Cerrado–Amazon transition. Many have tiny ranges and are seriously threatened. Similar to closely related genera such as '' Anablepsoides'', '' Atlantirivulus'', '' Cynodonichthys'' and '' Laimosemion'', ''Melanorivulus'' are jumpers and non-annual killifish. ''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, for data used in many areas of ichthyology, including taxonomy and fishery biology. Overall length Standard length (SL) is the length of a fish measured f ...

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 g ...

Brasil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

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 * Anthon ...

, 2011) * '' Melanorivulus spixi'' W. J. E. M. Costa, 2016 * '' Melanorivulus terena'' Volcan, Severo-Neto & Lanés, 2024 * '' Melanorivulus ubirajarai'' W. J. E. M. Costa, 2012 * '' Melanorivulus violaceus'' ( W. J. E. M. Costa, 1991) * '' Melanorivulus vittatus'' ( W. J. E. M. Costa, 1989) * '' Melanorivulus wallacei'' W. J. E. M. Costa, 2016 * '' Melanorivulus zygonectes'' ( G. S. Myers, 1927)

References

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