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.

Percina tanasi
Percina tanasi
(Snail Darter)
Native Transplant

Copyright Info
Percina tanasi Etnier, 1976

Common name: Snail Darter

Taxonomy: available through www.itis.govITIS logo

Identification: Page (1983); Page and Burr (1991); Etnier and Starnes (1993).

Size: 9 cm.

Native Range: Upper Tennessee drainage of eastern Tennessee, northern Georgia, and Alabama, including Little Tennessee River, Watts Bar Reservoir below Fort Loudon Dam, South Chickamauga Creek, lower portion of Big Sewee Creek in Meigs County, lower Sequatchie River in Marion County, Little River in Blount County, lower French Broad River in Sevier County, and lower Paint Rock River in Madison County, Alabama (Page and Burr 1991; Etnier and Starnes 1993).

Native range data for this species provided in part by NatureServe NS logo
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 Percina tanasi are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
TN197519895Hiwassee; Holston; Lower French Broad; Nolichucky; Upper Elk

Table last updated 7/13/2024

† Populations may not be currently present.

Ecology: Inhabits clean gravel or sandy shoals in large creeks and rivers (Boschung and Mayden 2004; Ashton and Layzer 2008). Prefers areas lacking aquatic macrophytes and with low degrees of turbidity or siltation (Ashton and Layzer 2008).

Diet primarily consists of snails, but also consumes trichopteran, dipteran, and ephemeropteran larvae (Boschung and Mayden 2004).

Means of Introduction: The Snail Darter was intentionally introduced to create an additional population of this endangered fish when its only known habitat was threatened by construction of a dam. Seven hundred and ten Snail Darters were introduced into the Hiwassee River from June 1975 to February 1976 (U.S. Fish and Wildlife Service 1982a; Etnier and Starnes 1993). In October 1975, 61 were introduced into the Nolichucky River. Introductions into the Nolichucky River were halted when the sharphead darter Etheostoma acuticeps was discovered there, for fear the introduction would jeopardize this rare species (U.S. Fish and Wildlife Service 1982a; Etnier and Starnes 1993). The Holston River was stocked with 533 Snail Darters from the Hiwassee and Little Tennessee rivers during the period 1978 to 1979. The Elk River was stocked in July 1980 with 425 Snail Darters from the Little Tennessee River (U.S. Fish and Wildlife Service 1982a).

Status: Established in Hiwassee River and range expanding (U.S. Fish and Wildlife Service 1982a). One darter observed in Nolichucky River in 1980. Single individual possibly from small reproducing population or escapee from fish hatchery upstream; none found since. Elk River populations apparantly extirpated due to failed introduction (Etnier and Starnes 1993). Snail Darters found in lower French Broad and lower Holston rivers in 1988 and 1989 presumably represent progeny of Holston River transplants (Etnier and Starnes 1993). In 2005, Ashton and Layzer (2008) found robust populations in French Broad and Hiwassee Rivers, and low abundances in Holston, Little, and Sequatchie Rivers and Big Sewee and South Chichamauga Creeks. Ashton and Layzer (2008) suggested that these low population sizes may be due to a lack of reproducing populations in these streams, with individuals migrating into these streams from larger, reproducing populations in French Broad and Hiwassee Rivers.

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: The Snail Darter was listed as a federally endangered species in 1975 (U.S. Fish and Wildlife Service 1982a). After several more populations were discovered in the early 1980s, the species' status was changed to threatened in 1984 (Etnier and Starnes 1993).

References: (click for full references)

Ashton, M.J. and J.B. Layzer. 2008. Distribution of the threatened snail darter (Percina tanasi) in the upper Tennessee River drainage. Journal of the Tennessee Academy of Science 83(3-4):52-56.

Boschung, H.T., and R.L. Mayden. 2004. Fishes of Alabama. Smithsonian Books, Washington, DC.

Etnier, D.A., and W.C. Starnes. 1993. The fishes of Tennessee. University of Tennessee Press, Knoxville, TN.

Lee, D.S., C.R. Gilbert, C.H. Hocutt, R.E. Jenkins, D.E. McAllister, and J.R. Stauffer, Jr. 1980 et seq. Atlas of North American freshwater fishes. North Carolina State Museum of Natural History, Raleigh, NC.

Page, L.M. 1983. Handbook of darters. T.F.H., Inc., Neptune City, NJ.

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

U.S. Fish and Wildlife Service. 1982a. Snail darter recovery plan.


Other Resources:
Species profile for Percina tanasi - U.S. Fish and Wildlife Service, Environmental Conservation Online System

Animal Diversity Web - Universit of Michigan Museum of Zoology

FishBase Summary

Author: Pam Fuller, and Matt Neilson

Revision Date: 8/16/2011

Peer Review Date: 8/16/2011

Citation Information:
Pam Fuller, and Matt Neilson, 2024, Percina tanasi Etnier, 1976: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?SpeciesID=827, Revision Date: 8/16/2011, Peer Review Date: 8/16/2011, Access Date: 7/13/2024

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 [7/13/2024].

Contact us if you are using data from this site for a publication to make sure the data are being used appropriately and for potential co-authorship if warranted.

For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.