Mexican rivulus

{{Short description|Species of fish}}

{{Speciesbox

| status = EN

| status_system = IUCN3.1

| status_ref = {{cite iucn |author=Lyons, T.J. |year=2019 |title=Millerichthys robustus |page=e.T19736A2482411 |doi=10.2305/IUCN.UK.2019-2.RLTS.T19736A2482411.en |access-date=19 November 2021}}

| image =

| parent_authority = W. J. E. M. Costa, 1995

| taxon = Millerichthys robustus

| authority = (R. R. Miller & C. L. Hubbs, 1974)

| synonyms = Rivulus robustus Miller & Hubbs, 1974

}}

The Mexican rivulus (Millerichthys robustus) is a species of killifish from the family Rivulidae which is endemic to Mexico where it is found in the Papaloapan and Coatzacoalcos River basins. This annual killifish grows to a total length of {{cvt|4|cm}}. It is the only known species in its genus, but its exact taxonomic position remains uncertain, as it has not been included in any phylogenetic study.{{FishBase species |genus= Millerichthys|species= robustus| month = October | year = 2012}}{{cite book | editor1=Berois, N. | editor2=G. García | editor3=R.O. de Sá | year=2015 | title=Annual Fishes: Life History Strategy, Diversity, and Evolution | page=22 | publisher=CRC Press | isbn=9781482299717 }} This species was described by Robert Rush Miller and Carl Leavitt Hubbs as Rivulus robustus in 1974,{{Cof record|spid=13648|title=Rivulus robustus|access-date=15 September 2019}} it was reclassified in the monotypic genus Millerichthys in 1995, the generic name honouring Robert Rush Miller.{{cite web | url = https://etyfish.org/cyprinodontiformes2/ | work = The ETYFish Project Fish Name Etymology Database | author1 = Christopher Scharpf | author2 = Kenneth J. Lazara | date = 20 March 2024 | title= Order CYPRINODONTIFORMES: Family RIVULIDAE | accessdate = 10 April 2024 | publisher = Christopher Scharpf and Kenneth J. Lazara|version=v. 16.0}}