The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Poeciliopsis sp.
Poeciliopsis sp.
(unidentified Poeciliopsis)
Native Transplant

Copyright Info
Poeciliopsis sp. Regan, 1913

Common name: unidentified Poeciliopsis

Synonyms and Other Names: livebearer, topminnow.

Taxonomy: available through www.itis.govITIS logo

Identification: Rauchenberger (1989b) listed 20 extant species in the genus Poeciliopsis. Rosen and Bailey (1963) provided diagnostic characters of the genus and a limited amount of information on the species known at that time. Distinguishing characteristics for species previously found in the United States were given by Page and Burr (1991). Photographs of several species appeared in Dawes (1991) and Wischnath (1993).

Size: 5.1-6 cm.

Native Range: Members of the genus Poeciliopsis occur in Pacific drainages from the southwestern United States to Colombia and in some Atlantic streams of southeastern Mexico, Guatemala, and Honduras (Rosen and Bailey 1963). Only one species, P. occidentalis, is native to the United States where it occurs in the Gila River system, New Mexico and Arizona, and in western Mexico; now extirpated in New Mexico (Page and Burr 1991).

Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Poeciliopsis sp. are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†

Table last updated 7/23/2024

† Populations may not be currently present.

Means of Introduction: Unknown. Possible aquarium release.

Status: Preumably failed in Connecticut.

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: Males of this genus have very long, pointed gonopodia which exhibit sinistral asymmetry (Dawes 1991).

References: (click for full references)

Dawes, J.A. 1991. Livebearing fishes. A guide to their aquarium care, biology and classification. Blandforn, London, England.

Page, L. M., and B. M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin Company, Boston, MA.

Whitworth, W. R. 1996. Freshwater Fishes of Connecticut. State Geological and Natural History Survey of Connecticut, Bulletin 114.

Other Resources:
FishBase Summary

Author: Nico, L.

Revision Date: 5/9/2019

Peer Review Date: 8/29/2001

Citation Information:
Nico, L., 2024, Poeciliopsis sp. Regan, 1913: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=867, Revision Date: 5/9/2019, Peer Review Date: 8/29/2001, Access Date: 7/24/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [7/24/2024].

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