# Tomeurus

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***Tomeurus gracilis*** is a species of [poeciliid](/source/Poeciliid) fish native to [South America](/source/South_America), in Brazil, Surinam and Venezuela. This species grows to a length of 3.3 centimetres (1.3 in) [TL](/source/Fish_measurement).[1] It is the only known member of its [genus](/source/Genus).[2] This species is classified in the [tribe](/source/Tribe_(biology)) [Cnesterodontini](/source/Cnesterodontini) in the 5th edition of [Fishes of the World](/source/Fishes_of_the_World),[3] but more recent classifications place it as the only member of the subfamily **Tomeurinae**, the **facultative viviparous poeciliids**.[4][5]

This is a sociable fish which lives in small schools consisting of several dozens of fishes. It is found in muddy creeks or along the sandy-muddy edges of shallow estuaries. It has been observed remaining still just below the surface but it prefers to hide beneath aquatic plants. Fertilisation is internal and, uniquely among the [Poeciliinae](/source/Poeciliinae), the females may then lay eggs placing them individually onto aquatic plants. They can also be facultively [ovoviviparous](/source/Ovoviviparous).[1]

## References

1. J. S. Nelson; T. C. Grande; M. V. H. Wilson (2016). [*Fishes of the World*](https://sites.google.com/site/fotw5th/). 5th ed. Wiley. p. 379. ISBN 978-1-118-34233-6.

1. Paulo Henrique Franco Lucinda & Roberto E. Reis (2005). "Systematics of the subfamily Poeciliinae Bonaparte (Cyprinodontiformes: Poeciliidae), with an emphasis on the tribe Cnesterodontini Hubbs". *Neotropical Ichthyology*. **3** (1): 1–60. [doi:10.1590/S1679-62252005000100001](https://doi.org/10.1590/S1679-62252005000100001)

1. ["CAS - Eschmeyer's Catalog of Fishes"](https://researcharchive.calacademy.org/research/ichthyology/catalog/fishcatmain.asp). *researcharchive.calacademy.org*. Retrieved 2025-03-15.

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Adapted from the Wikipedia article [Tomeurus](https://en.wikipedia.org/wiki/Tomeurus) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Tomeurus?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.