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==Description==
==Description==
The members of this genus generally have long, cylindrical bodies, relatively short fins and rounded [[caudal]]s.<ref name = "Innes">Exotic Aquarium Fishes, 1st Edition, by [[William T. Innes]], Innes Publishing Co., Philadelphia 1935</ref> A minority of species, such as ''R.'' ''lyricauda, R. mahdiaensis'' and ''R. rectocaudatus'', possess rectangular or lyre-shaped caudals. Individual species range in size from barely one inch long to over four inches. They are colored variously, many species being quite subdued in color with bright hues being notably absent, such as in ''R. atratus.'' However, the genus also includes numerous vividly colored species, such as ''R. strigatus,'' ''R. xiphidius'' and ''R. agilae,'' that are patterned with brilliant jewel-toned hues that are often iridescent. ''Rivulus'' frequently remain motionless for long periods of time, backs arched and tails pointed downward, and then dart suddenly to another location. They are all renowned jumpers and can remain out of water for long periods.<ref name=Innes/> There is a range of [[sexual dimorphism]] among the species in the genus. Males are generally more colorful or more intricately patterned. Females of many species display an [[ocellus]] at the upper base of the caudal fin. This is commonly known among aquarists as 'the rivulus spot'.<ref name=Innes/>
The members of this genus generally have long, cylindrical bodies, relatively short fins and rounded [[caudal]]s.<ref name = "Innes">Exotic Aquarium Fishes, 1st Edition, by [[William T. Innes]], Innes Publishing Co., Philadelphia 1935</ref> A minority of species, such as ''R.'' ''lyricauda, R. mahdiaensis'' and ''R. rectocaudatus'', possess rectangular or lyre-shaped caudals. Individual species range in size from barely one inch long to over four inches. They are colored variously, many species being quite subdued in color with bright hues being notably absent, such as in ''R. atratus.'' However, the genus also includes numerous vividly colored species, such as ''R. strigatus,'' ''R. xiphidius'' and ''R. agilae,'' that are patterned with brilliant jewel-toned hues that are often iridescent. ''Rivulus'' frequently remain motionless for long periods of time, backs arched and tails pointed downward, and then dart suddenly to another location. They are all renowned jumpers and can remain out of water for long periods.<ref name=Innes/> There is a range of [[sexual dimorphism]] among the species in the genus. Males are generally more colorful or more intricately patterned. Females of many species display an [[ocellus]] at the upper base of the caudal fin. This is commonly known among aquarists as 'the rivulus spot'.<ref name=Innes/>。It has also been found out that Rivulus killfish is one of the very few uncommon species that has both male and female genitals present on the same body. This means they are capable of producing offsprings by internally ovulating into themselves.


==Distribution and habitat==
==Distribution and habitat==

Revision as of 14:14, 19 September 2011

Rivulus
File:KillifishDM1710 468x378.jpg
Mangrove killifish (Rivulus marmoratus)
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Actinopterygii
Order:
Cyprinodontiformes
Family:
Rivulidae
Genus:
Rivulus

Poey, 1860
Species

See text.

Rivulus is a genus of freshwater fish in the Rivulidae family of Cyprinodontiformes. Over one hundred species of Rivulus have been described to date, some of them finding a degree of popularity among aquarists, especially killifish fanciers. The genus was erected by Cuban zoologist Felipe Poey in 1860 with the type species, Rivulus cylindraceus.[1]

Description

The members of this genus generally have long, cylindrical bodies, relatively short fins and rounded caudals.[2] A minority of species, such as R. lyricauda, R. mahdiaensis and R. rectocaudatus, possess rectangular or lyre-shaped caudals. Individual species range in size from barely one inch long to over four inches. They are colored variously, many species being quite subdued in color with bright hues being notably absent, such as in R. atratus. However, the genus also includes numerous vividly colored species, such as R. strigatus, R. xiphidius and R. agilae, that are patterned with brilliant jewel-toned hues that are often iridescent. Rivulus frequently remain motionless for long periods of time, backs arched and tails pointed downward, and then dart suddenly to another location. They are all renowned jumpers and can remain out of water for long periods.[2] There is a range of sexual dimorphism among the species in the genus. Males are generally more colorful or more intricately patterned. Females of many species display an ocellus at the upper base of the caudal fin. This is commonly known among aquarists as 'the rivulus spot'.[2]。It has also been found out that Rivulus killfish is one of the very few uncommon species that has both male and female genitals present on the same body. This means they are capable of producing offsprings by internally ovulating into themselves.

Distribution and habitat

Rivulus is the most geographically widespread genus of Neotropical aplocheiloid killifishes. Species are distributed as far north as Mexico and as far south as Argentina, including Central America, the Caribbean Islands, the Guiana Shield and the Amazon Basin. Throughout this range various species occupy lakes, ponds and streams in either sunny savannah or shaded forest habitats, most often in shallow waters. The species of this genus are non-annual. Rivulus, together with the closely related genera Prorivulus (erected in 2004 and containing a single species) and Kryptolebias (erected in 2004, comprising species formerly assigned to Rivulus), contain the only species in the family Rivulidae to inhabit perennial aquatic biotopes.[3]

Species

References

  • Froese, Rainer; Pauly, Daniel (eds.). "Species in genus Rivulus". FishBase. october 2007 version.
  1. ^ a b c Costa, Wilson J. (2007). "Rivulus bororo and R. paresi, two new killifishes from the upper Paraguay River basin, Brazil (Teleostei: Rivulidae)". Ichthyological Exploration of Freshwaters. 18 (4): 351–357.
  2. ^ a b c Exotic Aquarium Fishes, 1st Edition, by William T. Innes, Innes Publishing Co., Philadelphia 1935
  3. ^ Costa, Wilson J. E. M. "Relationships and taxonomy of the killifish genus Rivulus from the Brazilian Amazonas river basin, with notes on historical ecology". Aqua:Journal of Ichthyology & Aquatic Biology (Oct. 2006).
  4. ^ Costa, Wilson J. E. M. & Henrique Lazzarotto (2008). "Rivulus amanan, a new killifish from the Japurá river drainage, Amazonas river basin, Brazil (Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 19 (2): 129–134.
  5. ^ Costa, Wilson J. (2007). "A new species of Rivulus from the Claro river drainage, upper Paraná river basin, central Brazil, with redescription of R. pinima and R. vittatus (Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 18 (4): 313–323.
  6. ^ Costa, Wilson J. E. M. (2008). "Rivulus formosensis, a new aplocheiloid killifish from the upper Corrente River drainage, upper Paraná River basin, central Brazil (Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 19 (1): 85–90.
  7. ^ Costa, Wilson J. E. M. (2008). "Rivulus giarettai, a new killifish from the Araguari River drainage, upper Paraná River basin, Brazil (Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 19 (1): 91–95.
  8. ^ Costa, Wilson J. E. M. (2007). "Rivulus illuminatus, a new killifish from the serra dos Caiapós, upper rio Paraná basin, Brazil (Teleostei: Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 18 (3): 193–198.
  9. ^ Costa, Wilson 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. {{cite journal}}: line feed character in |title= at position 40 (help)
  10. ^ Costa, Wilson J. E. M. (2008). "Rivulus jurubatibensis, a new aplocheiloid killifish from the southeastern Brazilian coastal plains (Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 19 (2): 135–140.
  11. ^ Costa, Wilson J. (2007). "Rivulus kayabi, a new killifish from the Tapajós river basin, southern Brazilian Amazon (Cyprinodontiformes: Rivulidae)". Ichthyological Exploration of Freshwaters. 18 (4): 345–350.
  12. ^ Costa & Brasil; Brasil, Gilberto C. (2008). "A New Pelvicless Killifish Species of the Genus Rivulus, Subgenus Melanorivulus (Cyprinodontiformes: Rivulidae), from the Upper Tocantins River Basin, Central Brazil". Copeia. 2008 (1): 82–85. doi:10.1643/CI-07-079. {{cite journal}}: line feed character in |title= at position 61 (help)
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